Everything about Microspheres
RSS feed
  • Stainless Steel Microspheres

    300 Series stainless steel is well known for its corrosion resistant properties. Now Scientists are demanding high quality spherical stainless steel microspheres which offer high density (7.8g/cc), high sphericity (>90% round) and corrosion resistance (300 series stainless steel).

    A full range of precision sizes are now available from 1-22um on up to 1.0-1.2mm.

    Stainless Steel 250um (0.25mm) Spheres

    Stainless Steel 250um (0.25mm) Spheres

    Applications for Stainless steel spheres include.
    1) Conductive Spacers
    2) High Density Projectiles
    3) Charge Transport
    4) Shock Absorbtion

    Research vial quantities are listed, many sizes have kg quantities in stock for larger project needs.

  • Deformable Silver Coated PMMA Microsphere Spacers

    Silver Coated Glass Microspheres work well for increasing the conductivity of bond lines, but they lack the capability to deform when compressed to give increased conductive contact between the surfaces of the bond line.  These newly released Silver Coated PMMA Microspheres offer the low weight deformable pmma cores, and 250nm thick silver coating for high conductivity.

    Conductivity of this product has been measured at <0.5ohm per square with a 30% by volume preparation.  Sizes available cover both the common 50 micron (45-53um)  and 100 micron (90-106um) sizes and many others.

    These spheres are perfect for producing anisotropic (only conductive in one direction) conductive bond lines.

    Actual bond line thickness achieved will be a function of the assembly pressure and the size spheres selected.

    In addition to being high conductive these silver coated PMMA is bio-compatible.

  • Microspheres as bond line spacers in epoxies

    Today’s electronics are demanding tighter and tighter tolerances, and the assembly of many items require holding precise spacing between parts during assembly.  The spherical shape and precise sizes available make microspheres the ideal candidate as a precision spacer in various liquid adhesives and epoxies.

    Important considerations:

    1) The actual bond line will correspond to the largest spheres, not the average size.  Narrow size ranges of a few micron ensure the proper gap is maintained.

    • If a 30um gap is required use a spacer grade size range of 27-30 micron.
    • If a 40um gap is required use a spacer grade size range of 37-40 micron.
    • If a 53um gap is required use a spacer grade size range of 50-53 micron.

    3) Functionality gained from using different materials.

    • Glass offers the best mechanical and chemical stability at a wide range of temperatures.
    • Plastic such as PMMA can be used where some deformation is desirable.
    • Metal coated glass spheres can be used where conductivity is desirable.
    • Hollow Glass spheres can be used where assembly pressures are low, and reduced thermal conductivity is desired, available as uncoated hollow glass or silver coated hollow glass spheres.

    4) The importance of sphere loading (% spheres by volume in the adhesive)

    • Theoretical maximum loading by volume for a monolayer is 61%
    • A mixture of about 5% by volume should work for most applications.
    • Narrow bond lines with high assembly forces will require higher loadings
    • Low crush strength spheres will require higher loadings.
    • Proper dispersion in the adhesive will help to minimize the loading needed.

    5) Adhesive / Epoxy selection

    • High viscosity epoxies will help maintain sphere dispersion.
    • For best results choose an adhesive that adheres to the spheres and the base material.
    • Long pot-life materials work best, as they allow excess adhesive to flow out of the bond line during assembly.

    6) Spacer Availability – Cospheric LLC stocks a wide variety of sizes and materials, and can custom produce spacer grade microspheres for your application.

    Applications for Bond Line Spacers

    Image courtesy of Nikkei Business PublicationsSpacer Grade Glass Microspheres are presently used in gas plasma displays, automotive mirrors, electronic displays, flip chip technology, filters, sporting goods equipment, calibration standards and transformer manufacturing.  Every day engineers are finding new and innovative uses for bond line spacers.  One area that has had the most publications is in die attachment in the semi-conductor industry, a particularly interesting area is in using spacers for building multi-die packages. Continue reading “Microspheres as bond line spacers in epoxies” »

  • Advantages of Borosilicate Glass Microspheres in 0.03mm to 0.2mm sizing

    Borosilicate Glass Microbeads

    BSGMS 63-75 micron at 40x magnification

    High quality glass microspheres for research and development are always in high demand.  In an effort to better serve scientists Cospheric recently added a complete line of high quality borosilicate microspheres, and microbeads.

    Borosilicate glass offers  advantages over standard soda lime glass microbeads.

    • Roundness is >90%   (Soda lime >85%)
    • Density is the lowest of most glasses at 2.2g/cc  (Soda Lime 2.5g/cc)
    • Very low thermal expansion coefficient  32×10-7/°C   (for 30-300°C)   (Soda Lime:  90×10-7/°C)

    The high roundness, and low thermal expansion make borosilicate spheres an excellent candidate for use as spacers in epoxy bond lines, or other applications which require stability over a wide temperature range.

    Borosilicate glass spheres are now offered in narrow size ranges from 0.03mm to 0.2mm with greater than 90% of the particles in range.

    Continue reading “Advantages of Borosilicate Glass Microspheres in 0.03mm to 0.2mm sizing” »