KR20150060728A - Microsphere-filled-metal components for wireless-communication towers - Google Patents

Abstract

Lt; RTI ID = 0.0 > at least < / RTI > partially formed from microsphere-filled metal. The microsphere-filled metal has a density of less than 2.7 g / cm ³ , a thermal conductivity of greater than 1 W / m · K, and a thermal expansion coefficient of less than 30 μm / m · K. Suitable microspheres for use in such microsphere-filled metals are, for example, glass microspheres, mullite microspheres, alumina microspheres, alumino-silicate microspheres, ceramic microspheres, silica- Spheres, and mixtures of two or more thereof.

Description

[0001] MICROSPHERE-FILLED-METAL COMPONENTS FOR WIRELESS-COMMUNICATION TOWERS FOR WIRELESS COMMUNICATIONS [

<Reference to related application>

This application claims benefit of U.S. Provisional Application No. 61 / 707,085 filed on September 28, 2012.

Various embodiments of the present invention are directed to metal-based components for use in a wireless telecommunications tower.

In the field of telecommunications, bandwidth requirements are expected to increase globally every year to support new services and an increased number of users, and therefore wireless systems are expected to migrate to higher frequency bands. In this industry, there is a trend to move the base station electronics from a tower base to a higher area of the radio telecommunication tower (i.e., top-to-top electronics), which tends to reduce signal loss in telecommunication cables connecting the tower top to the base equipment Effort. Since an increased number of parts are moved to the tower, the weight of these parts becomes a problem.

In one embodiment,

A wireless telecommunications tower component formed at least partially from a microsphere-filled metal,

Wherein the microsphere-filled metal has a density of less than 2.7 grams per square centimeter ("g / cm &lt; ³ &gt;

Various embodiments of the present invention are directed to wireless telecommunications tower components formed at least partially from a metal-based material. Such metal-based materials may have particular properties, including a particular range for density, thermal conductivity and coefficient of thermal expansion, making them suitable for top-top applications. Such wireless telecommunications tower components may in particular include radio frequency ("RF") cavity filters, heat sinks, enclosures, tower-top support accessories, and combinations thereof.

Metal-based material

As noted, the wireless telecommunications tower component can be formed at least in part from the metal-based material. As used herein, a "metal-based" material is a material comprising a metal as a major (ie, greater than 25 weight percent ("wt%")) component. In various embodiments, the metal-based material may comprise one or more metals in a combined amount of at least 50, at least 60, at least 70, at least 80, at least 90, or at least 95 wt%. In some embodiments, the at least one metal comprises all or substantially all of the metal-based material. As used herein, the term "substantially all" individually indicates the presence of less than 10 parts per million (ppm) of the undesired component. In an alternative embodiment, the metal-based material may be a composite of a metal and one or more fillers, as described in more detail below, so that one or more metals may be added in a lower ratio (e.g., Up to 99% by weight).

The metal component of the metal-based material may be any metal or combination of metals (i. E., A metal alloy) known in the art or found later. In various embodiments, the metal-based material may comprise a low density metal such as aluminum or magnesium, or other metals such as nickel, iron, bronze, copper, and alloys thereof. In one or more embodiments, the metal-based material may comprise a metal alloy, such as aluminum or magnesium, and alloys thereof. In certain embodiments, the metal-based material comprises aluminum. In various embodiments, aluminum comprises at least 50, at least 60, at least 70, at least 80, at least 90, at least 95 weight percent, substantially all, or all of the metal component of the metal-based material. Thus, in various embodiments, the metal-based material may be an aluminum-based material. In addition, the aluminum used may be an aluminum alloy, such as AA 6061. Alloy 6061 typically contains 97.9 wt.% Aluminum, 0.6 wt.% Silicon, 0.28 wt.% Copper, 1.0 wt.% Magnesium, and 0.2 wt.% Chromium.

As mentioned above, the metal-based material may have certain characteristics. In various embodiments, the metal-based material is 2.7 grams / cubic centimeters ( "g / cm ^3") is less than, 2.6 g / cm ³ less than, 2.5 g / cm ³ less than, 2.4 g / cm ³ less than, 2.3 g / cm ^3, less than 2.2 g / cm ^3, less than 2.1 g / cm ³ , or less than 2.0 g / cm ³ . In such embodiments, the metal-based material may have a density of at least 0.1 g / cm &lt; ³ &gt;. Because the metal-based material may comprise a polymer-metal composite as discussed below, the density values provided herein may be measured at 25 占 폚 in accordance with ASTM D792. For non-polymer / metal-composite material, the density can be measured according to ASTM D1505 by the density gradient method.

In various embodiments, the metal-based material has a specific surface area greater than 1 watt / meter Kelvin ("W / mK"), greater than 2 W / mK, greater than 3 W / 5 W / m · K, or 6 W / m · K. In such embodiments, the metal-based material may have a thermal conductivity of 50 W / mK or less, 100 W / mK or less, 180 W / mK or less, or 250 W / mK or less. All of the thermal conductivity values provided herein are measured at 25 DEG C in accordance with ISO 22007-2 (transient plane heat source [high temperature disk] method). In various embodiments, the metal-based material is less than 40 micrometers per meter Kelvin ("μm / mK", which is equivalent to ppm / , A linear isotropic coefficient of thermal expansion ("CTE") of less than 35 μm / m · K, less than 30 μm / m · K, or less than 26 μm / m · K. In such an embodiment, the metal-based material may have a CTE of at least 10 [mu] m / mK. All CTE values provided herein are measured according to the procedure provided in the Test Methods section below.

In various embodiments, the metal-based material has a tensile strength of at least 5.0 megapascals ("MPa"). In this embodiment, the metal-based material generally has an ultimate tensile strength of 500 MPa or less. Because the metal-based materials described herein are also related to polymer-metal composites, all of the tensile strength values provided herein are measured in accordance with ASTM D638. For metal-only samples, the tensile properties are measured according to ASTM B557M.

In various embodiments, the metal-based material may be a foamed metal. As used herein, the term "foam metal" refers to a metal having a cell-like structure comprising void-space pores of a certain volume fraction. The metal of the foamed metal may be any metal known in the art as being suitable for producing foamed metal or found later. For example, the metal of the foamed metal may be selected from aluminum, magnesium and copper, and alloys thereof, among others. In certain embodiments, the foamed metal may be foamed aluminum.

In various embodiments, the foamed metal may have a density in the range of 0.1 to 2.0 g / cm ³ , 0.1 to 1.0 g / cm ³ , or 0.25 to 0.5 g / cm ³ . In some embodiments, the foamed metal may have a relative density of 0.03 to 0.9, 0.1 to 0.7, or 0.14 to 0.5, wherein the relative density (in units) is less than the base metal (i.e., Of the density of the foamed metal to the density of the foamed metal. In addition, the foamed metal may have a thermal conductivity in the range of 5 to 150 W / mK, 8 to 125 W / mK, or 15 to 80 W / mK. In addition, the foamed metal may have a CTE in the range of 15 to 25 μm / m · K, or 19 to 23 μm / m · K. In various embodiments, the foamed metal may have a tensile strength in the range of 5 to 500 MPa, 20 to 400 MPa, 50 to 300 MPa, 60 to 200 MPa, or 80 to 200 MPa.

In various embodiments, the foam metal may be a closed-cell foam metal. As is known in the relevant art, the term "closed-cell" refers to a structure in which most of the pore-space pores in the metal-based material are independent pores (i.e., are not interconnected with other pore-space pores). The closed-cell foamed metal may generally have a cell size in the range of 1 to 8 millimeters ("mm").

In various embodiments, the foam metal may be an open-cell foam metal. As is known in the relevant art, the term "open-cell" refers to a structure in which most of the pore-space pores in the metal-based material are interconnected pores (i.e., in open contact with one or more adjacent pores). The open-cell foamed metal may generally have a cell size in the range of 0.5 to 10 mm.

Commercially available foamed metals may be used in the various embodiments described herein. For example, suitable foamed aluminum materials can be obtained from Isotech Inc in sheet form or in three-dimensional cast form. This material also forms ^TM Tech Corporation may each be obtained in a sheet form from the (Foamtech ^TM Corporation), La mat bibeuyi ^{TM (TM} Racemat BV), and red ^TM International Corporation ^(TM Reade International Corporation).

In various embodiments, particularly when an open-cell foamed metal is used, the foamed metal may be either (a) a non-foamed metal, or (b) a portion of a surface region or surface region coated with a polymer- can do. In such embodiments, the foamed metal may thus provide a surface that is substantially free (i.e., smooth) without defects. Such a surface can facilitate metal plating and enable the formation of parts that require a smooth surface, such as in the case of a heat sink fin where the desired strength may not be achieved by the foam structure alone. Also, the fins generally have a thickness that does not add substantial weight to the structure, thus retaining the non-foamed structure for additional strength or filling the void-space pores of the foamed structure with the polymer-based material (or At least partially filling) may be preferred. When the surface area is non-foamed, the non-foamed portion may have an average depth from the surface in the range of 0.05 to 5 mm. An example of a suitable foamed metal having a non-foamed surface area is a stabilized aluminum foam commercially available from Alusion ^TM , a division of Cymat Technologies, Toronto, Canada.

An additional approach to improving the heat loss of the foamed metal is to use a foam core that allows air circulation without affecting the overall performance of the article, such as, for example, holding a sealing enclosure to protect the enclosed component It may be to use an air passage to pass through. This approach is particularly useful when a non-foamed outer layer is used, i. E. It occurs only in the core through a channel in which the circulation is reasonably located.

When polymer-based materials are used to provide a defect-free or substantially defect-free surface, or to fill or at least partially fill the foam structure for additional strength, such polymer- To a thickness that ranges from fully penetrating the metal to forming an interpenetrating polymer-metal network. Examples of polymer-based materials for use in such embodiments include thermosetting epoxies, or thermoplastic amorphous or crystalline polymers. In one embodiment, the polymer-based material is a thermosetting epoxy. The polymer-based material may be applied to the surface area using any conventional method or method that will be found later, or may be made to penetrate into the structure of the foamed metal. For example, such application can be accomplished through vacuum casting or pressure impregnation, or insert molding with a thermosetting material under pressure. The polymeric material may itself be filled with a suitable filler for density reduction, heating strength and / or thermal conductivity improvement. Such fillers may include silica, quartz, alumina, boron nitride, aluminum nitride, graphite, carbon black, carbon nanotubes, aluminum flakes and fibers, glass fibers, glass or ceramic microspheres, and combinations of two or more thereof.

In various embodiments, the metal-based material may be a microsphere-filled metal. As used herein, the term "microsphere" refers to a filler material having a mass median diameter ("D50") of less than 500 micrometers ("μm"). Microsphere fillers suitable for use herein may generally have a spherical or substantially spherical shape. The metal of the microsphere-filled metal may be any of the metals described above. As mentioned above, the metal of the metal-based material may be aluminum. Thus, in certain embodiments, the microsphere-filled metal may be microsphere-filled aluminum.

In various embodiments, the microsphere-filled metal may have a density in the range of 0.6 to 2 g / cm &lt; ³ &gt;. In addition, the microsphere-filled metal may have a thermal conductivity in the range of 5 to 150 W / mK. In addition, the microsphere-filled metal may have a linear isotropic CTE in the range of 8 to 25 μm / m · K. In various embodiments, the microsphere-filled metal may have a tensile strength in the range of 0.8 to 60 Kpsi (~ 5.5 to 413.7 MPa).

Various types of microsphere fillers may be used in the microsphere-filled metal suitable for use herein. In various embodiments, the microsphere filler is hollow. In addition, in certain embodiments, the microspheres are selected from the group consisting of glass microspheres, mullite microspheres, alumina microspheres, aluminosilicate microspheres (also known as cenosphere), ceramic microspheres, silica- , Carbon microspheres, and mixtures of two or more thereof.

In various embodiments, the microspheres suitable for use herein may have a particle size distribution D10 of from 8 to 30 [mu] m. Additionally, the microspheres may have a D50 of 10 to 70 [mu] m. In addition, the microspheres may have a D90 of 25 to 120 [mu] m. In addition, the microspheres may have a true density in the range of 0.1 to 0.7 g / cm &lt; ³ &gt;. As is known in the relevant art, "true" density is a density measure that ignores intergranular void spaces (as opposed to "bulk" density). The true density of the microspheres can be measured with a helium gas displacement type dry automatic density meter (e.g., Acupic 1330 from Shimadzu Corporation) as described in European Patent Application No. EP 1 156 021 A1 have. In addition, the microspheres suitable for use herein may have a CTE in the range of 0.1 to 8 [mu] m / mK. In addition, microspheres suitable for use may have a thermal conductivity in the range of 0.5 to 5 W / m 占.. The microspheres can be metal coated.

In various embodiments, the microspheres may comprise from 1 to 95 volume percent ("volume%"), from 10 to 80 volume%, or from 30 to 70 volume%, based on the total volume of the microsphere-filled metal.

In one or more embodiments, the microspheres may optionally be combined with one or more types of conventional filler materials. Examples of typical filler materials include silica and alumina.

Commercially available microsphere-filled metals may be used in the various embodiments described herein. One example of one such commercially available product is SComP ™ from Powdermet Inc. (Euclid, Ohio, USA).

In various embodiments, the microsphere-filled metal may provide a portion of a surface region or surface region that is (a) a non-microsphere-filled metal or (b) coated with a polymer-based material. In such an embodiment, the microsphere-filled metal may thus provide a surface that is defect free or substantially free (i.e., smooth), which may facilitate metal plating and may require a smooth surface For example, a heat sink pin). When the surface area is non-microsphere-filled, the non-microsphere-filled portion may have an average depth from the surface in the range of 0.2 to 5 mm.

When a polymer-based material is used to provide a defect-free surface, such a polymer-based material may be applied in a thickness in the range of 50 to 1,000 [mu] m. Examples and methods of using a polymer-based material for use in this embodiment are the same as described above with respect to the foamed metal.

Wireless Telecommunication Tower Parts

As mentioned above, any one or more of the above-described metal-based materials may be used to at least partially fabricate wireless telecommunications tower parts. As used herein, "wireless telecommunications tower part" refers to any piece of electronic communication equipment, a satellite positioning system ("GPS") equipment, or similar equipment, or parts or parts thereof. Although the term "tower" has been used, such equipment need not actually be designed to be mounted on a tower or mounted on a tower, but rather another high location, such as a radio mast, building, monument or wood may also be considered. Examples of such components include, but are not limited to, antennas, transmitters, receivers, transceivers, digital signal processors, control electronics, GPS receivers, power supplies, and enclosures for electrical component housings. In addition, components typically found in such electrical equipment, such as RF filters and heat sinks, are also contemplated. In addition, top-top support accessories, such as platforms and mounting hardware, are also included.

As mentioned above, the radio telecommunication tower part may be an RF filter. An RF filter is a key element within a remote radio head. An RF filter is used to remove a signal of a specific frequency and is generally used as a building block for a duplexer and a diplexer to combine or separate multiple frequency bands. RF filters also play a major role in minimizing interference between systems operating in different bands.

RF cavity filters are commonly used RF filters. A common practice for fabricating such filters of various designs and physical geometries is to die-cast aluminum into the desired structure or to machine the final geometry from the die-cast preform. The RF filter, its features, its fabrication, its machining and its overall fabrication are described, for example, in U.S. Patent Nos. 7,847,658 and 8,072,298.

As mentioned above, the polymer-based material may be used to provide a smooth surface on the metal-based material and / or may be used as a filler for the metal-based material. For example, an epoxy composite material can be used to coat at least a portion of the surface of the metal-based material. Exemplary epoxy composites are described in United States patent application serial number 61 / 557,918 ("'918 application"). In addition, the surface of the metal-based material and / or the polymer-based material may be metallized as described in the '918 application.

 In various embodiments, at least some of the metal-based materials described above may be metal plated, as is typically done for RF cavity filters. For example, a metal layer, such as copper, silver, or gold, may be deposited on the metal-based material or the intervening polymer-based material layer through a variety of plating techniques. Examples of suitable plating techniques can be found, for example, in the '918 application.

In one embodiment, the wireless telecommunications tower part may be a heat sink. As is known in the relevant art, a heat sink, which may be a component used in a remote radio head, typically includes a base member and a heat spreading member (or "pin"). The heat spreading member is typically formed from a highly conductive material, such as copper. In one embodiment, a heat sink manufactured in accordance with the present disclosure may comprise a base member formed from any of the above-described metal-based materials and uses conventional heat spreading members. In various embodiments, when a foamed metal (particularly an open-cell foamed metal) is used, the base member may have a non-foamed surface as described above.

In various embodiments, the wireless telecommunications tower part may be an enclosure that contains and / or protects electronic equipment. An example of such an enclosure may be the MRH-24605 LTE remote radio head, for example from MTI Inc.

In one or more embodiments, the wireless telecommunications tower component may be a support member, e.g., a part used to fabricate a fastening bracket or platform. Specific components include but are not limited to antenna mounts, support brackets, co-location platforms, clamping systems, sector frame fittings, ice bridge kits, tri-sector t-mount fittings, light kit mounting systems, and wave- It is not.

Fabrication of the wireless telecommunications tower components described above from the metal-based materials described herein may be performed according to any known or later discovered metal-processing technique, such as molding, bending, die-casting, machining, and combinations thereof .

<Test Method>

density

The density of the composite sample is measured at 25 DEG C in accordance with ASTM D792. For metal-only samples, the density is measured according to ASTM D1505 by the density gradient method.

Thermal conductivity

The thermal conductivity is measured according to ISO 22007-2 (transient plane heat source (high temperature disc) method).

Coefficient of thermal expansion

The CTE is measured using a Thermomechanical Analyzer (TMA 2940 from TA Instruments). A heating rate of 5 [deg.] C / min is used to generate the expansion profile and the CTE is calculated as the slope of the expansion profile curve as follows: CTE = DELTA L / (DELTA TxL) (M), L is the original length (m) of the sample, and DELTA T is the change in temperature (DEG C). The temperature range at which the tilt is measured is 20 占 폚 to 60 占 폚 in the second heating.

The tensile strength

Tensile properties measurements (tensile strength and% elongation at break) are made on epoxy formulations cured according to ASTM D638 using a Type 1 tensile bar and a strain rate of 0.2 inch / min. For aluminum metal samples, tensile properties are measured according to ASTM B557M.

The glass transition temperature (Tg)

Tg is measured by placing the sample in a differential scanning calorimeter ("DSC ") having a first heating scan from 0 to 250 占 폚 and heating and cooling at 10 占 폚 / min in a second heating scan from 0 to 250 占 폚. Record the Tg as the half-height value of the second transition at the second heating scan from 0 to 250 占 폚.

<Examples>

Example 1 - Comparison of materials

The samples of foamed aluminum (S1) in Table 1 were compared with conventional aluminum (Comparative Example A), three epoxy composite compositions (Comparative Examples B to D), and glass-filled polyetherimide (Comparative Example E) . Foamed aluminum was a 25.4 mm thick sample with a density of 0.41 g / cm &lt; ³ &gt; and a mainly open-cell structure, and was obtained from SiMat Technologies, The normal aluminum was an aluminum alloy 6061. The mixing, casting and curing processes for the epoxy composite compositions (Comparative Examples B to D) were generally carried out as described below. The glass-filled polyether imide was ULTEM ^TM 3452, a polyether ether imide having 45% glass fiber filler, commercially available from GE Plastics.

Comparative Examples B to D Manufacturing procedures

The terms and names used in the following description are as follows: D.E.N. 425 is an epoxy resin with an EEW of 172 and is commercially available from The Dow Chemical Company; D.E.R. 383 is an epoxy resin having an EEW of 171 and is commercially available from The Dow Chemical Company; "NMA" refers to methyl anhydride and is commercially available from Polysciences; "ECA100" refers to Epoxy Curing Agent 100, commercially available from Dixie Chemical, and ECA 100 generally comprises greater than 80% methyltetrahydrophthalic anhydride and greater than 10% tetrahydrophthalic acid An anhydride; "1MI" refers to 1-methylimidazole, commercially available from Aldrich Chemical; SILBOND 占 W12EST is an epoxy silane treated quartz with a D50 particle size of 16 占 퐉 and is commercially available from Quarzwerke.

The required amount of filler was dried overnight in a vacuum oven at a temperature of ~ 70 ° C. The epoxy resin containing the anhydride solidifying agent was preliminarily heated to ~ 60 ° C. The amount of warm epoxy resin, warm anhydrous solidifying agent and 1-methylimidazole were loaded into a large plastic container with an inlet, which was manually diluted, followed by the addition of warm filler. The contents of the vessel were then mixed on a FlackTek SpeedMixer ™ at a number of cycles of from about 800 to about 2000 rpm for a duration of 1-2 minutes.

The combined blends were loaded with a vacuum pump for degassing and a vacuum controller into a temperature controlled ~500 to 1000-mL resin kettle with an overhead stirrer using a glass stirrer and holding Teflon ® blades . A typical degassing profile was performed at about 55 ° C to about 75 ° C, the following steps being representative: 5 minutes, 80 rpm, 100 Torr; 5 min, 80 rpm, 50 Torr; 5 minutes, 80 rpm, N ₂ brakes from 20 Torr to ~ 760 Torr; 5 minutes, 80 rpm, N ₂ brakes from 20 Torr to ~ 760 Torr; 3 min, 80 rpm, 20 Torr; 5 min, 120 rpm, 10 Torr; 5 min, 180 rpm, 10 Torr; 5 min, 80 rpm, 20 Torr; And 5 minutes, 80 rpm, 30 Torr. Depending on the size of the compound to be degassed, the time at higher vacuum may optionally be increased, as well as a higher vacuum of 5 Torr if desired.

The warm degassed mixture was poured into the warm mold assembly described below at atmospheric pressure. For the particular molds described below, a specific amount of typically about 350 grams to 450 grams was poured on the open side of the mold. The filled mold was placed vertically in an 80 DEG C oven for about 16 hours, subsequently raised in temperature and held at 140 DEG C for a total of 10 hours; Subsequently the temperature was subsequently raised and held at 225 DEG C for a total of 4 hours; It was then slowly cooled to ambient temperature (about 25 DEG C).

Mold assembly

Each Duo foil (DUOFOIL) (~ 330 mm x 355 mm x ~ 0.38 mm) was secured onto two ~ 355 mm ² metal plates with angled cuts at one corner. Silicone rubber tubing (used as a gasket) with ~ 3.05 mm thick U-spacer rod and ~ 3.175 mm ID x ~ 4.75 mm OD was placed between the plates and the mold was held closed using a C-clamp. The molds were pre-warmed in an oven at about &lt; RTI ID = 0.0 &gt; 65 C &lt; / RTI &gt; The same mold process can be adapted for use with thicker U-spacer rods, as well as being adapted for casting using smaller metal plates, but also with appropriate adjustment of the silicone rubber tubing serving as a gasket have.

<Table 1> Comparison of materials for wireless communication tower parts

N / D = not measured

* Typical 6061 alloy (unmeasured; data available from www.efunda.com)

** Characteristics not measured; Data was obtained from the GI products data sheet and recorded

*** Flow direction / transverse direction

† The plating procedure was performed according to the description provided in the US patent application Serial No. 61 / 557,918

†† Foamed aluminum with good skin finish provides a platable surface.

As shown in Table 1, foamed aluminum provided a lower coefficient of thermal expansion compared to thermoset, and maintained adequate thermal conductivity at significantly reduced density compared to conventional aluminum.

Example 2 - Foam aluminum filled with thermosetting epoxy

The foamed aluminum block having dimensions of 2 "x2" x0.5 "was cast and cured in a filled epoxy formulation according to the following procedure: The epoxy formulation used was DER 332 + 50/50 methyl anhydride / epoxy hardener 100 (i. E., MTHPA) and 65 wt% Silicone Bond 126. The foamed aluminum foams were the same as described above in Example 1. The epoxy compositions were mixed and degassed as described above, The container was sealed and air was removed from the aluminum foam by applying a vacuum for 35 minutes as described below to remove the liquid epoxy from the metal &lt; RTI ID = 0.0 &gt; Pushed into the pores: 10 torr for 10 minutes, 5 torr for 5 minutes, 10 torr for 5 minutes, 20 torr for 5 minutes, and 30 torr for 5 minutes. A 550-mil thick U-spacer was placed in the mold and about one-half of the degassed mixture was poured into a mold assembly (described above), where the epoxy-absorbed aluminum foam pieces were in place And the remaining epoxy was poured on top. Curing was carried out at 80 DEG C for 16 hours, then at 140 DEG C for 10 hours and finally at 200 DEG C for 4 hours.

The resulting composites had an average density of 1.65 g / cm ³ , an average CTE in the range of 23.6 to 29.4 μm / m · K, and a linear isotropic thermal conductivity of 5.1 W / m · K.

Claims (10)

A wireless telecommunications tower component formed at least partially from a microsphere-filled metal,
Wherein the microsphere-filled metal has a density of less than 2.7 grams per square centimeter ("g / cm &lt; ³ &gt; The apparatus of claim 1, wherein the metal of the microsphere-filled metal is selected from the group consisting of aluminum, magnesium, and alloys thereof. The microsphere-filled metal of claim 1 or 2, wherein the microsphere-filled metal has a thermal conductivity of greater than 1 watt / meter Kelvin ("W / mK & ("CTE") of less than 30 micrometers / meter Kelvin (" 4. A method according to any one of claims 1 to 3, wherein the microsphere-filled metal has a density in the range of 0.6 to 2 g / cm &lt; ³ &gt; at 25 DEG C and 5 to 150 W / m · K and has a linear isotropic CTE in the range of 8 to 25 μm / m · K over a temperature range of -35 to 120 ° C. 5. The apparatus of any one of claims 1 to 4, wherein the microsphere-filled metal has a tensile strength in the range of 0.8 to 60 Kpsi. 6. The method of any one of claims 1 to 5, wherein the microsphere-filled metal is selected from the group consisting of glass microspheres, mullite microspheres, alumina microspheres, alumino-silicate microspheres, ceramic microspheres, , Carbon microspheres, and mixtures of two or more thereof. The method of claim 6, wherein the microsphere has a D90 of D50, and 25 to 120 μm range of the particle size distribution D10, 10 to 70 μm range of 8 to 30 μm range, Jean of 0.1 to 0.7 g / cm ³ range Density. 7. The apparatus of claim 6, wherein the microspheres comprise from 1 to 95 volume percent based on the total volume of the microsphere-filled metal. 9. A method according to any one of claims 1 to 8, wherein the wireless telecommunication tower component is selected from the group consisting of a radio frequency ("RF") cavity filter, a heat sink, an enclosure, A device that is selected. 10. The apparatus according to any one of the preceding claims, wherein the radio telecommunication tower part is an RF cavity filter and at least a portion of the microsphere-filled metal is copper and / or silver plated.