Metal-Coated Microspheres – Conductive Coating

Applications of Metal-Coated Microspheres:

Metal-Coated Microspheres - Hollow Glass

Metal-Coated Microspheres – Nickel-Coated Hollow Glass (Cospheric LLC Product ID: HGMS-Ni)

From early days engineers have been looking for ways to shield circuits from electromagnetic interference (EMI). One of the most effective methods of EMI shielding is to build an electrically conductive enclosure around the circuit or device. This can be accomplished by using any electrically conductive material. Advances in manufacturing of metal-coated microspheres have enabled the creation of lightweight electrically conductive coatings that provide excellent EMI shielding.

Metal-coated microspheres are often used as a conductive filler that is lighter than solid metal additives in paints, adhesives, and composites to provide electrical conductivity. They are also used as catalysts, laser fusion targets, and electrically conducting bond line spacers in advanced electronics and other applications. In addition, low particle density and large surface area facilitates slow phase separation in paints and adhesives compared to heavy metallic and inorganic fillers.

Manufacturing of Metal-Coated Microspheres:

Electrically conductive microspheres are produced by applying a metallic silver coating to the surface of the microspheres, thus combining the advantages of a metal particle with the additional benefits of the spherical shape of the core.

Types of Metal-Coated Microspheres:

Silver-Coated Hollow Glass Microspheres:

Conductive Metal-Coated Solid Glass Microspheres

Conductive Metal-Coated Solid Glass Microspheres (Cospheric LLC Product ID: SLGMS-Ag )

Silver is often the metal coating of choice because it is durable, highly reflective, antibiotic, and offers a controlled conductive and EMI shielding surface for use as an exceptional conductive filler for demanding applications.

Typically hollow glass microspheres are silver coated as this offers the combination of a low density filler and a conductive particle. Metal coatings with EMI shielding of greater than 45db have been produced by adding as little as 20% by weight of M-18 silver coated microspheres.

Conductive hollow glass microspheres have low particle densities and so provide a significant weight reduction when used in place of conventional conductive fillers such as solid silver particles. A range of products offers particles with a variety of diameters, densities and crush strengths. HGMS-AG / HCMP-AG product lines were specifically designed for applications in biotechnology and as a tracer particle in Particle Image Velocimentry (PIV) which often require a true particle density higher than 1g/cm3 or just slightly lower at 0.9g/cm3.

Silver-Coated Solid Glass Microspheres:

Highly conductive silver metal coated solid soda lime glass microspheres are offered as a dry powder and are designed for use in Anisotropic Conductive Films and Adhesives, also known as ACF and ACT. Solid glass conductive spheres allow interconnection of circuit lines through the adhesive thickness (the Z-Axis), but are spaced far enough apart for the product to be electrically insulating along the plane of the adhesive. Solid glass spheres, as opposed to hollow glass, provide a durable material that is easy to work with and withstands force and demanding environments.

Silver-Coated Monodisperse Silica Microspheres:

Conductive Bondline Spacer - Silver-Coated Silica Spheres

Conductive Bondline Spacer – Silver-Coated Silica Spheres (Cospheric LLC Product ID: SiO2MS-Ag)

Silver-coated silica m are formed of a silica microsphere interior coated in a thin layer of silver metal, providing silica microspheres with the unique electrical conductivity and reflectivity of silver while holding to a tight particles distribution of a CV less than 10%. This high precision silica material offers a small and uniform precision conductive spacer option for LCD displays and other electrical components.

Silver-Coated Polymer Microspheres – Deformable Spacer:

Silver Coated Poly(Methyl Methacrylate) microspheres and microparticles with conductive coating are available in sizes between 5um and 750um in free-flowing dry powder form. PMMA cores with conductive silver coating are ideal where some deflection is required while maintaining conductivity and compliance. These particles can be used as conductive deformable spacers in bondline applications and offer benefits for Ansiotropic Conductive Film (ACF) applications, creating conductivity in one direction. The combination of the thick coating of the silver and the bonding to the compliant deformable polymer sphere offers a durable solution.

Nickel-Coated Hollow Glass Microspheres:

These hollow glass microspheres are coated with nickel metal to create electrically conductive microspheres to be used as a lightweight filler in paints, adhesives, and composites to provide electrical conductivity. Due to their low density and high crush strength, nickel-planted glass microspheres are useful as a filler in automotive, aerospace, electronics and construction materials. They provide reduced part weight and improve dimensional stability. Nickel-coating is often selected when an economical cost is more critical than superior performance.

Retroreflective Aluminum Coating on Solid Glass Microspheres:

Retroreflective Aluminum-Coated Microspheres

Retroreflective Aluminum-Coated Microspheres (Cospheric LLC Product ID: P2453)

Aluminum (Al) coatings on microspheres offer advantages in developing retroreflective surfaces for high visibility materials and applications. The hemispherical (half-shell) aluminum coating creates the mechanism for retroreflectivity as the light passes through the clear half of the glass bead and “bounces” off the reflective aluminum-coated back surface, directing the light back to the source or the viewer.

Additional surface coatings (silane or fluorochemical) on top of the aluminum coating ensure that the spheres remain on the surface of the formulation, thereby enhancing the effect of retroreflectivity.

Full Aluminum Coating on Solid High Density Glass Microspheres:

Solid Barium Titanate Glass Spheres with Full Aluminum Coating are durable opaque particles with a reflective surface, which offer high density and opacity offer a unique high-visibility solution to imaging in ultrasonic systems, optics, and x-rays.

Gold Coating on Solid High Density Glass Microspheres:

Gold-Coated Microspheres - Roundness and Sphericity of Microparticles

Gold-Coated Microspheres (Cospheric LLC Product ID: BTGSM-Au)

Gold (Au) is a durable, conductive, and highly reflective coating material suitable for a wide variety of applications of metal-coated microspheres. It is a good conductor of both heat and electricity. Gold-coated microspheres are produced by applying a thin gold coating on microspheres creates a controlled slightly conductive surface of spherical particles with well-defined shape and particle size distribution, which does not tarnish or corrode.

Options for Materials for Metal-Coated Microspheres:

As described above many different options for metal coating and spherical core are currently commercially available. Custom formulations of metal-coated micropsheres are also possible for special projects when leadtime and budgets allow for research and development opportunities.