RADIATION-SHIELDED THERMAL INTERFACE

Description

TECHNICAL FIELD

Some embodiments pertain to electronic packaging for space applications. Some embodiments relate to radiation shielding.

BACKGROUND

One issue with housing electronic packages intended for space applications is that heat sinking is needed to protect the electronics from incurring damage due to heat while at the same time protecting the electronics from damage caused by ionizing radiation. Conventionally, external radiation shields have been used to protect the electronics. These external radiation shields are not suitable for radiating applications such as those that use antennas.

Thus, there are needs for improved techniques for housing electronic packages intended for space applications that provide heat sinking as well as ionizing radiation protection. There are also needs for techniques for housing electronic packages intended for space applications that use antennas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a composite housing assembly in accordance with some embodiments.

FIG. 2 illustrates a brazed joint between the housing and the radiation shielding element of FIG. 1, in accordance with some embodiments.

FIG. 3 illustrates a cross section of a joining region between the housing and the radiation shielding element of FIG. 1, in accordance with some embodiments.

FIG. 4 illustrates a composite housing assembly that includes unshielded electronics and shielded electronics, in accordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims.

Some embodiments are directed to radiation-shielded thermal interface comprising a low-density material joined with a very high-density material. Some embodiments are directed to a composite housing assembly for shielding electronic components. The composite housing assembly may include a housing comprising a low-density material and a radiation shielding element comprising a very high-density material. Some embodiments are directed to a method for joining a low-density material a very high-density material. These embodiments, as well as others are described in more detail below.

In some embodiments, a radiation-shielded thermal interface comprising a low-density material is joined with a very high-density material. An interface material is deposited on faying surfaces of the very high-density material and low-density material using an ion-vapor deposition process. The very high-density material and the low-density material may be joined together by a vacuum brazing process using a braze filler. The very high-density material may comprise a radiation shielding element and may be positioned within a housing made of the low-density material to provide ionizing radiation shielding for shielded electronics within the housing. The housing may provide heat sinking for the shielded electronics by thermal conduction through the radiation shielding element.

FIG. 1 illustrates a composite housing assembly 100 in accordance with some embodiments. The composite housing assembly 100 may be configured for shielding electronic components. The composite housing assembly may comprise a housing 102 and a radiation shielding element 104. The housing 102 may be comprised of a low-density material and the radiation shielding element 104 may be comprised of a very high-density material. In these embodiments, the radiation shielding element 104 and the housing 102 may be joined together by a vacuum brazing process using a braze filler. In these embodiments, prior to the vacuum brazing process, faying surfaces 106 of the housing 102 and radiation shielding element 104 may be coated with an interface material.

FIG. 2 illustrates a brazed joint between the housing 102 and the radiation shielding element 104 of FIG. 1, in accordance with some embodiments. Brazed joint 206 may be formed by joining the radiation shielding element 104 and the housing 102 by a vacuum brazing process using a braze filler. This is described in more detail below.

FIG. 3 illustrates a cross section of a joining region between the housing 102 and the radiation shielding element 104 of FIG. 1, in accordance with some embodiments. In these embodiments, the radiation shielding element 104 and the housing 102 may be joined together by a vacuum brazing process using a braze filler 306. In these embodiments, prior to the vacuum brazing process, faying surfaces 106 (FIG. 1) of the housing 102 and radiation shielding element 104 may be coated with an interface material 304.

Referring to FIGS. 1-3 , in some embodiments, the very high-density material may comprise a refractory metal selected from the group consisting of Tungsten (W), Molybdenum (Mo) and Tantalum (Ta), the low-density material may comprise a metal matrix composite material comprising one or more of beryllium and aluminum, and the braze filler 306 may comprise an aluminum-silicon (Al—Si) alloy. In these embodiments, the interface material 304 may comprise aluminum or an aluminum alloy deposited around the entire faying surfaces 106 by one of an ion-vapor deposition process, a cold spray process and an electro-deposition process.

In some embodiments, the very high-density material may comprise a refractory metal matrix composite that includes a refractory metal selected from the group consisting of Tungsten (W), Molybdenum (Mo) and Tantalum (Ta).

In some embodiments, the very high-density material has a density of at least 16 g/cm³ and the low-density material has a density of no greater than 3 g/cm³ although the scope of the embodiment is not limited in this respect as the density of the very high-density material may range from as low as 4 g/cm³ to up to 20 g/cm³ or greater.

In some embodiments, the very high-density material may comprise Tungsten (W) (density of 19.28 g/cm³), the low-density material may comprise a beryllium and aluminum metal matrix composite material (density of 2.071-2.3 g/cm³), and the braze filler 306 may comprise an aluminum-silicon (Al—Si) alloy. In these embodiments, the interface material 304 may comprise aluminum or an aluminum alloy deposited around the entire faying surfaces 106 by an ion-vapor deposition process.

In some of these embodiments, the beryllium and aluminum metal matrix composite material may be derived by a powder metallurgy process. An example of a suitable beryllium and aluminum metal matrix composite is an aluminum-beryllium metal composite that is comprised of 62% commercially pure beryllium and 38% pure aluminum. In some of these embodiments, the interface material 304 and braze filler 306 provides a metallurgical bond between the housing 102 and the radiation shielding element 104. In some of these embodiments, examples of Al—Si alloys suitable for use as the braze filler 306 may include BAiSi-2, BAlSi-5, BAlSi-4. In some embodiments, high-purity active braze alloy of silver, copper and titanium (e.g., Ag—Cu—Ti) based alloys may also be used for the braze filler 306.

In some embodiments, the very high-density material may comprise Tantalum (Ta) (density of 16.65 g/cm³) or Tantalum alloy (density of 16.6 to 16.8 g/cm³), and the low-density material may comprise Aluminum (Al) (density of 2.7 g/cm³) or an Aluminum alloy (densities 2.640-2.810 g/cm³).

In other embodiments, Titanium (density of 4.51 g/cm³), Titanium alloys (density of 4.25 to 4.84 g/cm³), Stainless Steel (density of 7.5 to 8.0 g/cm³), or Copper Cu (density of 8.96 g/cm³) may be used in lieu of the very high-density material and Aluminum (Al) or an Aluminum alloy may be used as the low-density material. In some of these embodiments, a titanium, stainless steel or copper element may serve as a thermal barrier or conductive interface.

In some embodiments, the thickness of the interface material 304 is approximately one-thousandth of an inch (1 mil) (25.4 micrometers) (e.g., ranging from about 0.9 to 1.1 mils) (22.8 to 28 microns) however, the scope of the embodiments is not limited in this respect as thicknesses of up to 6 mils and even 10 mils may be also be suitable. In these embodiments, a thickness of the radiation shielding element 104 may range between 30 and 50 mils (762 to 1270 micrometers) in thickness although the scope of the embodiments is not limited in this respect.

In some embodiments, the radiation shielding element 104 may be positioned within the housing 102 to provide ionizing radiation shielding for shielded electronics 404 within the housing 102. In these embodiments, the housing 102 may provide heat sinking for the shielded electronics 404 by thermal conduction through the radiation shielding element 104. In some of these embodiments, radiation shielding element 104 provides for both ionizing radiation shielding and heat sinking for shielded electronics 404 within the housing 102 while the housing 102 may provide little or no ionizing radiation shielding for any unshielded electronic components which may be within the housing 102.

Referring to FIGS. 1-3, some embodiments are directed to a composite housing assembly 100 for housing electronic components comprising a housing 102 made from a low-density material and a radiation shielding element 104 made from a very high-density material. In these embodiments, the radiation shielding element 104 and the housing 102 may be joined together by a vacuum brazing process using a braze filler 306. In these embodiments, prior to the vacuum brazing process, faying surfaces 106 of the housing 102 and radiation shielding element 104 may be coated with an interface material 304. In these embodiments, the radiation shielding element 104 may be positioned within the housing 102 to provide ionizing radiation shielding for shielded electronics 404 within the housing 102. In these embodiments, the housing 102 may provide heat sinking for the shielded electronics 404 by thermal conduction through the radiation shielding element 104.

In some of these embodiments, the very high-density material has a density of at least 16 g/cm³ and the low-density material has a density of no greater than 3 g/cm³.

In these embodiments, the very high-density material may comprise Tungsten (W), and the low-density material may comprise a beryllium and aluminum metal matrix composite material. In some of these embodiments, the braze filler 306 may comprise an aluminum-silicon (Al—Si) alloy and the interface material 304 may comprise aluminum or an aluminum alloy deposited around the entire faying surfaces 106 by an ion-vapor deposition process.

Referring to FIGS. 1-3, some embodiments are directed to a radiation-shielded thermal interface comprising a low-density material joined with a very high-density material, and an interface material 304 deposited on faying surfaces 106 of the very high-density material and low-density material using an ion-vapor deposition process. In these embodiments, the very high-density material and the low-density material may be joined together by a vacuum brazing process using a braze filler 306. The very high-density material may comprise a radiation shielding element 104.

In these embodiments, the very high-density material may comprise a refractory metal selected from the group consisting of Tungsten (W), Molybdenum (Mo) and Tantalum (Ta) and the low-density material may comprise a metal matrix composite material comprising one or more of beryllium and aluminum. The braze filler 306 may comprise an aluminum-silicon (Al—Si) alloy and the interface material 304 may comprise aluminum or an aluminum alloy deposited around the entire faying surfaces 106 by one of an ion-vapor deposition process, a cold spray process and an electro-deposition process.

In some embodiments, the very high-density material may comprise a refractory metal matrix composite that includes a refractory metal selected from the group consisting of Tungsten (W), Molybdenum (Mo) and Tantalum (Ta).

In some of these embodiments, the very high-density material has a density of at least 16 g/cm³ and the low-density material has a density of no greater than 3 g/cm³ although the scope of the embodiment is not limited in this respect as the density of the very high-density material may range from as low as 4 g/cm³ to up to 20 g/cm³ or greater. In these embodiments, the very high-density material may comprise Tungsten (W), the low-density material may comprise a beryllium and aluminum metal matrix composite material, the braze filler 306 may comprise an aluminum-silicon (Al—Si) alloy, and the interface material 304 may comprise aluminum or an aluminum alloy deposited around the faying surfaces 106 by an ion-vapor deposition process.

In some embodiments, the very high-density material may comprise Tantalum (Ta) or Tantalum alloy. In some embodiments, the low-density material may comprise Aluminum (Al) or an Aluminum alloy.

Some embodiments are directed to a method for joining a low-density material a very high-density material. In these embodiments, the method may include depositing an interface material 304 on faying surfaces 106 of the very high-density material and low-density material using a deposition process. In these embodiments, the method may also include joining the very high-density material and the low-density material together by a vacuum brazing process using a braze filler 306. In these embodiments, the very high-density material is configured as a radiation shielding element 104 and the low-density material is configured as a housing 102. In these embodiments, the very high-density material may comprise a refractory metal selected from the group consisting of Tungsten (W), Molybdenum (Mo) and Tantalum (Ta), and the low-density material may comprise a metal matrix composite material comprising one or more of beryllium and aluminum. In these embodiments, the braze filler 306 may comprise an aluminum-silicon (Al—Si) alloy, and the interface material 304 may comprise aluminum or an aluminum alloy deposited around the entire faying surfaces 106 by one of an ion-vapor deposition process, a cold spray process and an electro-deposition process.

FIG. 4 illustrates a composite housing assembly 400 that includes unshielded electronics 402 and shielded electronics 404, in accordance with some embodiments. In some embodiments, the unshielded electronics 402 may include an antenna assembly and front-end electron components although the scope of the embodiments is not limited in this respect.

As illustrated in FIG. 4, the composite housing assembly 400 may be configured for attachment of unshielded electronics 402 (FIG. 4) provided on a side of the housing adjacent to the radiation shielding element 104 opposite the shielded electronics 404 (FIG. 4). In these embodiments, radiation shielding element 104 may provide ionizing radiation shielding between the unshielded electronics 402 and the shielded electronics 404.

These embodiments allow for enablement of radiating applications such as antennas and provided improves thermal performance by providing intimate contact between the shielding element and the heatsink element thereby increasing the available material available for heat sinking.

In some embodiments, the housing 102 may be produced by casting or additive processes in addition to conventional powder metallurgical techniques. Elements attached to the housing may be wrought material or made from a casting or powder metallurgy or additive manufacturing techniques.

Vacuum brazing is a specialized brazing process performed in a vacuum chamber. For vacuum brazing, the parts to be joined are thoroughly cleaned and assembled with brazing filler metal, the assembly is placed in a vacuum furnace which removes oxygen and other atmospheric gases (preventing oxidation), the parts are heating to brazing temperature (typically 800-2000° F. depending on materials) and precise temperature control is maintained. Vacuum brazing is a challenge for joining Tungsten and a beryllium and aluminum metal matrix composite material since Tungsten has an extremely high melting point (˜3400° C./6152° F.) and the beryllium and aluminum metal matrix composite material has a much lower melting point (˜660° C./1220° F. for the aluminum matrix). Joining Tungsten and a beryllium and aluminum metal matrix composite material is also a challenge due to the significant difference in thermal expansion coefficients between the materials. Accordingly, a braze filler 306 comprising an aluminum-silicon (Al—Si) alloy may be used along with an interface material 304 comprising aluminum or an aluminum alloy that is deposited around the entire faying surfaces by one of an ion-vapor deposition process. Faying refers to the surfaces that will be joined together in any welding, brazing, or similar joining process. The faying surfaces are the interfaces that will make direct contact and form the bond. Proper preparation of faying surfaces (like cleaning, degreasing, and sometimes roughening) is crucial for achieving a strong joint.

EXAMPLES

Example 1: A method for joining a low-density material a very high-density material, the method comprising: depositing an interface material on faying surfaces of the very high-density material and low-density material using a deposition process; and joining the very high-density material and the low-density material together by a vacuum brazing process using a braze filler.

Example 2: The method of example 1, wherein the very high-density material is configured as a radiation shielding element and the low-density material is configured as a housing.

Example 3: The method of example 2, wherein the very high-density material comprises a refractory metal selected from the group consisting of Tungsten (W), Molybdenum (Mo) and Tantalum (Ta), and wherein the low-density material comprises a metal matrix composite material comprising one or more of beryllium and aluminum, wherein the braze filler comprises an aluminum-silicon (Al—Si) alloy, and wherein the interface material comprises aluminum or an aluminum alloy deposited around the faying surfaces by one of an ion-vapor deposition process, a cold spray process and an electro-deposition process.

Example 4: The method of example 3, wherein the very high-density material has a density of at least 16 g/cm³ and the low-density material has a density of no greater than 3 g/cm³.

Example 5: The method of example 4, wherein the very high-density material comprises Tungsten (W), and wherein the low-density material comprises a beryllium and aluminum metal matrix composite material, wherein the braze filler comprises an aluminum-silicon (Al—Si) alloy, and wherein the interface material comprises aluminum or an aluminum alloy deposited around the faying surfaces by an ion-vapor deposition process.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.