Copper Diamond Composites Research Articles

Cold Sprayed Copper-Diamond Composites for Thermal Management of Semiconductor Packages

Thermal management is key to enabling increasingly powerful chips and heterogeneous integrated 2.5D/3-D systems. Composite materials with high thermal conductivities that can be placed at different levels of proximity to the die provide new solutions for heat dissipation. Here we report the fabrication of thick copper-diamond composite films using cold spray, which is a high-throughput, low-thermal-budget deposition technology. In cold spray, feedstock micro powder is accelerated in a specially designed nozzle by a heated pressurized gas and adheres to the substrate upon high-speed impingement. This process achieves higher deposition rates than other methods used in semiconductor manufacturing (such as electroplating). It also produces films that are denser and much less porous than ones produced by conventional thermal spray techniques. In this work, we first use process and thermal simulations to determine the requirements of the micro diamond powder feedstock, including the diamond core size, metal-clad thickness, core-clad interfacial resistance, and volume fraction to enable the cold spray of copper-diamond composites with thermal conductivities that are higher than copper. Subsequently, we perform a systematic characterization of the diamond powders from several suppliers, including the purity, metal oxygen content, particle morphology, and metal-clad adhesion. This characterization reveals the challenges of meeting all the specs using currently available diamond powders. Finally, we cold spray copper-diamond composite films on a variety of substrates with tunable thicknesses between 100 mm and 2 mm, achieving a thermal conductivity that is approximately 10% higher than cold-sprayed pure copper. Further improvement of the thermal properties relies on continued innovation in powder surface modification and powder storage/shipping methods.

Enhancing wear resistance, hardness, and thermal conductivity of copper diamond composites through optimization strategies

Enhancing wear resistance, hardness, and thermal conductivity of copper diamond composites through optimization strategies

The Influence of the Carbide-Forming Metallic Additives (W, Mo, Cr, Ti) on the Microstructure and Thermal Conductivity of Copper–Diamond Composites

In this study, carbide-forming metallic additives (W, Mo, Cr, Ti) were introduced into the copper matrix to improve the wettability of diamond particles in the copper–diamond composites. The samples were prepared by Spark Plasma Sintering (SPS) and Hot Pressing (HP) at 920 °C. The phase composition, microstructure and thermal conductivity of the samples were investigated. The influence of the carbide-forming additive concentration, the sintering method as well as the nature of the metal introduced into the copper matrix on the thermal conductivity of copper–diamond composites was determined. Titanium ensured a more significant wettability improvement at the copper–diamond interface. This is due to its higher solubility in copper in comparison with other metals (W, Mo, Cr) and the possibility of its diffusion through the copper matrix to the diamond surface resulting in the formation of a closer contact at the copper–diamond interface.

Tribological, mechanical and thermal response of diamond micro-particles reinforced copper matrix composites fabricated by powder metallurgy

Copper/Diamond composites have gained a lot of attention in recent years due to their excellent thermal conductivity and their potential for use in high-power electronic devices. The current work targets on an experimental investigation of the tribological,mechanical, and thermal behaviour of copper diamond composite by using reinforced micro-diamond particles. Copper matrix composites with varying weight percentages of diamond particles were produced with the aid of the powder metallurgy. The wear tests were carried out on Pin-on-Disc wear test machine as per ASTM G99. The doping of an optimum amount of diamond particles (1% wt.) improved the overall wear performance by 51% under a normal load of 80 N. The doping had also showed a significant improvement in hardness by 26% and thermal conductivity by 1%. The primary wear mechanisms of Cu-Diamond composites appear to be a combination of brittle fracture, fragmentation of diamond-reinforced particles and ploughing in the Cu-alloy matrix.

Experimental Investigation on Tribological Behaviour of Copper Diamond Composites

In the present study, a range of copper diamond composites were prepared using powder metallurgy. The impact of volume fraction of diamond on tribological behaviour and its effective dispersion with copper powder was studied. Composites containing dispersion of hard particles in a metal matrix are widely used for automotive and other structural applications. Sliding wear has a vital role in the performance of electrical sliding contacts used in electric and electronic devices. Thermal considerations are also equally important for the sustainability of electronic parts. Product life and its reliability of sliding contacts are directly proportional to wear phenomenon. Due to these reasons and to meet the demands of improving thermal properties of materials for electronic components, a new composite material composed of diamond and copper was developed. The ball mill was used for 4 hours at 300 rpm for grinding and blending copper, diamond into fine powder. Being a cost-effective technique, normal sintering and powder metallurgy method were adopted for composite preparation where spark plasma sintering and other techniques were found to be very costly. Diamond was added in different volume fraction (1% wt., 3% wt. and 5% wt.) as reinforcement to analyse the influence of diamond particle concentration, distribution and its particle size on thermal conductivity and wear behaviour. A transmission electron microscope was used to characterize the morphology of powder. XRD analysis was used to identify the crystalline phases present in the composites. A wear test was performed on pin on disk test rig. The wear test illustrated that higher diamond content improves the wear resistance of the composite.

Retraction Note: Enhanced tensile strength and thermal conductivity in copper diamond composites with B4C coating

Editor's Note: this Article has been retracted; the Retraction Note is available at https://www.nature.com/articles/10.1038/s41598-022-25431-8

The influence of morphology and composition of metal–carbide coatings deposited on the diamond surface on the properties of copper–diamond composites

In this work, tungsten- and molybdenum-containing coatings on diamond were obtained by rotary chemical vapor deposition (RCVD) or by treating the diamond microcrystals in a hot press (HP)/spark plasma sintering (SPS) facility. In the HP facility, heating was realized by external heating elements; no electric current was passing through or induced in the die. In RCVD, tungsten carbonyl W(CO)6 was used as a precursor. In the case of HP and SPS, powders of tungsten, molybdenum and tungsten trioxide WO3 were used as sources of the metal. It was found that the morphology and phase composition of the coatings depend on the deposition conditions and the metal source. HP and SPS were further used for fabricating bulk copper–50 vol% diamond composites. The thermal conductivity of the copper–diamond composites decreased as the holding time during their consolidation by HP or SPS increased owing to delamination of the WC coating from the diamond surface. A Mo-containing coating deposited by the SPS treatment allowed obtaining a copper–diamond composite with a thermal conductivity of 420 W m−1 K−1.

Comparative study on the properties and microscopic mechanism of Ti coating and W coating diamond-copper composites

Interface plays a decisive role in metal matrix composites, and the effects of Ti coating and W coating on the properties and microscopic mechanism of diamond-copper composites are compared in this paper. Ti-coated diamond with 50 nm, 100 nm and 150 nm plating thickness and W-coated diamond with 50 nm plating thickness are prepared by using magnetron sputtering. Then infiltration method is carried out to prepare diamond copper composites. SEM, EDS and XRD are used to material microstructure. Three-point bending experiment and flash method are used to test the bending strength and thermal conductivity of the composite material. The study found that, as the thickness of the Ti coating increases, the bending strength of the composites gradually increases, but the thermal conductivity first increases and then decreases. The thermal conductivity of W coated diamond copper composites is higher than that of Ti coated diamond copper composites with the same coating thickness. But bonding strength shows the opposite law. The reason for the above phenomenon is that the mechanism of action between the Ti coating and the W coating and the copper substrate is different at the micro interface of the composites. The research work has important reference value for the interface modification of diamond copper composites.

An Improved Control Chart for Monitoring Linear Profiles and its Application in Thermal Conductivity

In most of the manufacturing processes, we encounter different quality characteristics of a product and process. These characteristics can be categorized into two kinds; study variables (variable of interest) and the supporting/explanatory variables. Sometime, a linear relationship might exist between the study and supporting variable, which is called simple linear profiles. This study focuses on the simple linear profiles under assorted control charting approach to detect the large, moderate and small disturbances in the process parameters. The evaluation of the proposed assorted method is assessed by using numerous performance measures, for instance, average run length, relative average run length, extra and sequential extra quadratic losses. A comparative analysis of the proposal is also carried out with some existing linear profile methods including Shewhart_3, Hotelling's T2, EWMA_3, EWMA/R and CUSUM_3 charts. Finally, a real-life application of the proposed assorted chart is presented to monitor thermal management of diamond-copper composite.

Titanium-Doped Copper-Diamond Composites Fabricated by Hot-Forging of Powder Mixtures or Cold-Pressed Powder Preforms

Cu-55 vol.%diamond-1 vol.%Ti composites were fabricated by hot-forging of powder mixtures (referred to as M-Cu/Dia) and cold-pressed powder preforms (referred to as P-Cu/Dia). Dispersion of diamond particles in the size range of 70–80 µm at 55% volume fraction was attained in the P-Cu/Dia composites while diamond agglomerations were observed in the M-Cu/Dia composites. TiC was observed at the copper/diamond interface in both composites, in which most diamond particle surfaces (> 95%) were enveloped by TiC. It was found that TiC formed preferentially on the diamond-{100} facets compared with the diamond-{111} facets, which can be attributed to the fact that the C atoms are bonded by two C–C bonds on the diamond-{100} facets (more active) while three C–C bonds on the diamond-{111} facets (less active). The dispersion of diamond particles and formation of a TiC interface layer contributed to the thermal conductivity (388 W/mK) of the P-Cu/Dia composites, which is nearly twice that of pure copper hot-pressed from powder.

Improvement of ZrC/Zr Coating on the Interface Combination and Physical Properties of Diamond-Copper Composites Fabricated by Spark Plasma Sintering.

In this study, diamond-copper composites were prepared with ZrC/Zr-coated diamond powders by spark plasma sintering. The magnetron sputtering technique was employed to coat the diamond particles with a zirconium layer. After heat treatment, most of the zirconium reacted with the surface of diamond and was transformed into zirconium carbide. The remaining zirconium on the zirconium carbide surface formed the outer layer. Owing to the method used to produce the ZrC/Zr-coated diamond in this study, the maximum thermal conductivity (TC) of 609 W·m−1·K−1 was obtained for 60 vol. % diamond-copper composites and the corresponding coefficient of thermal expansion (CTE) reached as low as 6.75 × 10−6 K−1. The bending strength of 40 vol. % ZrC/Zr-coated diamond-copper composites reached 255.95 MPa. The thermal and mechanical properties of ZrC/Zr-coated diamond-copper composites were substantially superior to those of uncoated diamond particles. Excellent properties can be attributed to the strengthening of the interfacial combination and the decrease in the interfacial thermal resistance due to the improvement associated with the ZrC/Zr coating. Theoretical analysis was also proposed to compare the thermal conductivities and CTE of diamond-copper composites fabricated with these two kinds of diamond powders.

Fabrication and Wear Performance of (Cu–Sn) Solution/TiCx Bonded Diamond Composites

The Cu(Sn)–TiCx bonded diamond composites were prepared by in situ reaction sintering of Cu, Ti2SnC and diamond powders. Effect of Ti2SnC content on the phase composition, microstructure and grinding properties were studied. The result shows that Ti2SnC was decomposed to TiCx and Sn. And then, Sn atom dissolved into the crystal lattice of Cu and formed Cu(Sn) solution. The rich C formed at the interface between diamond and the matrix. Excess Ti2SnC inhibited the formation of Cu solid solution and reacted with Cu to form Cu3Sn. Additionally, its matrix was mainly composed of TiCx with better wear resistance, which may improve obviously the grinding performance of the composites. The grinding ratio value of copper–diamond composite was only 132. The grinding ratio value of the composite contained higher Ti2SnC content in the raw materials was 636.

Effect of the Surface Modification of Synthetic Diamond with Nickel or Tungsten on the Properties of Copper–Diamond Composites

Tungsten- and nickel-containing coatings have been produced on the surface of synthetic diamond crystals by rotary chemical vapor deposition (RCVD) using tungsten hexacarbonyl, W(CO)6, and nickelocene, Ni(C5H5)2, as gaseous precursors. The thickness, composition, and morphology of the coatings have been shown to depend on the RCVD process duration and reactant concentrations in the vapor phase. The synthetic diamond microcrystals with tungsten- and nickel-containing coatings have been used to produce copper–diamond heat-conducting composites. Powder mixtures containing 50 vol % diamond with a particle size of 50, 100, or 200 μm have been consolidated by spark plasma sintering or hot pressing. It has been shown that the highest relative density (97%) and thermal conductivity (340 W/(m K)) are offered by the composites produced by spark plasma sintering using tungsten carbide-coated 50-μm diamond crystals.

Reaction fabrication and wear performance of TiCx/(Cu–A1) bonded diamond composites

AbstractCu–TiCx-bonded diamond composites were prepared by in-situ reaction sintering of Cu, Ti3AlC2, and diamond powders. The effect of Ti3AlC2 content on the phase composition, microstructure, and grinding properties was investigated. Ti3AlC2 was decomposed to TiCx and Al. Then, Al was dissolved into the crystal lattice of Cu to form a Cu(Al) solution. A carbon-rich transition layer was formed at the interface between the diamond and the matrix. Excess Al inhibited the formation of Cu solid solution and reacted with Cu to form Cu3Al2. Diamond may be damaged to some extent by adding excess Ti3AlC2 in the raw materials, which may deteriorate the grinding performance of the composites. The grinding ratio value of copper–diamond composite was only 132, whereas that of the composites containing higher Ti3AlC2 content in the raw materials was approximately 350.

RETRACTED ARTICLE: Enhanced tensile strength and thermal conductivity in copper diamond composites with B4C coating

Boron carbide (B4C) coating on diamond particle is synthesized by heating diamond particles in a powder mix of H3BO3 and B in Ar atmosphere. The composition, bond state and coverage fraction of boron carbide coating on diamond particles are investigated. The boron carbide coating favors to grow on diamond (100) surface rather than on diamond (111) surface. Cu matrix composites reinforced with B4C-coated diamond particles were made by powder metallurgy. The addition of B4C coating gave rise to a dense composite. The influence of B4C coating on both tensile strength and thermal conductivity of the composite were investigated. When the B4C fully covered on diamond particles, the composite exhibited a greatly increase in tensile strength (115 MPa) which was much higher than that for uncoated-diamond/Cu (60 MPa) composites. Meanwhile, a high thermal conductivity of 687 W/mK was achieved in the B4C-coated-diamond/Cu composites.

Morphological features of W- and Ni-containing coatings on diamond crystals and properties of diamond-copper composites obtained by Spark Plasma Sintering

In the present study, W- and Ni-containing coatings on diamond crystals were obtained by rotary chemical vapor deposition (RCVD) using tungsten carbonyl W(CO)6 and nickelocene Ni(C5H5)2 as precursors. Morphological features of the coatings deposited under different processing conditions were investigated. For obtaining bulk diamond-copper composites, mixtures of the coated and uncoated diamond crystals with a copper powder were subjected to Spark Plasma Sintering (SPS). The effects of the presence of the coatings on the diamond crystals and the size of the initial diamond particles on the microstructure, relative density and thermal conductivity of the consolidated diamond-copper composites were investigated.

Structure and properties of the graphene and diamond-copper composites fabricated by the high pressure-high temperature method

Structure and properties of the graphene and diamond-copper composites fabricated by the high pressure-high temperature method

Cu/synthetic and impact-diamond composite heat-conducting substrates

Composite material with high thermal conductivity was obtained by the method of thermal sintering of diamonds (synthetic and impact) and copper powder and by further hot isostatic pressing. The content of diamond (the particle size is 20 - 250 μm) in the diamond copper composite was 30 - 45 weight percent. The coefficient of thermal conductivity of copper diamond composite materials based on synthetic diamonds was measured to be 700 - 750 Wm-1K-1. The coefficient of thermal conductivity of copper diamond composite materials based on impact diamonds was measured to be 850 - 900 Wm-1 K-1. The coefficient of thermal expansion (CTE) was measured to be 5.5 - 6.5 • 10-6/°C for synthetic diamonds and 6.1 - 6.5 •10-6/°C for impact diamonds. The obtained copper diamond composite materials are promising to be used as crystal holders for semiconductor crystals in THz and microwave devices.

Effect of Transient Thermal Loads on Tungsten Monoblock Module in DEMO

Thermo-hydraulic analyses of the tungsten mono-block divertor module with a water cooling tube made from a diamond/copper composite (DCC) as a laminate and a martensitic steel EUROFER against the power loadings expecting in DEMO operation is presented. Thermal analysis is carried out by using the code MEMOS, which simulates W armor damage under the repetitive edge localized modes (ELM) heat impact. Heat transfer to the water coolant is studied for various coolant conditions which allow one to keep the material temperatures within the allowable design limits under neutron irradiation. The thermal performance is analyzed for the DEMO I and DEMO II reactor conditions for un-mitigated and mitigated ELMs. The importance of W vapor shielding effect is discussed.

Mechanical properties of a diamond–copper composite with high thermal conductivity

Abstract Using pressureless infiltration of copper into a bed of coarse (180 μm) diamond particles pre-coated with tungsten, a composite with a thermal conductivity of 720 W/(m K) was prepared. The bending strength and compression strength of the composite were measured as 380 MPa. As measured by sound velocity, the Young's modulus of the composite was 310 GPa. Model calculations of the thermal conductivity, the strength and elastic constants of the copper–diamond composite were carried out, depending on the size and volume fraction of filler particles. The coincidence of the values of bending strength and compressive strength and the relatively high deformation at failure (a few percent) characterize the fabricated diamond–copper composite as ductile. The properties of the composite are compared to the known analogues — metal matrix composites with a high thermal conductivity having a high content of filler particles (~ 60 vol.%). In strength and ductility our composite is superior to diamond–metal composites with a coarse filler; in thermal conductivity it surpasses composites of SiC–Al, W–Cu and WC–Cu, and dispersion-strengthened copper.