Everything about Microspheres
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  • 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.

  • Calculating microspheres per gram

    During scientific experiment design and analysis it is common to need to know the number of spheres per gram of dry material.  We have put together the table below to help speed up the process.

    If you have material of a density different from those listed in the table, divide the number of spheres per gram in the density ~1.0 g/cc column by the true particle density of your material to get an estimate of the number of spheres per gram.

    Product Size Polyethylene
    Density ~1.0 (g/cc)
    Soda Lime Glass
    Density ~2.5 (g/cc)
    Lower (um) Upper (um) Spheres per Gram Spheres Per Gram
    20 27 147,162,715 58,630,564
    27 32 74,393,558 29,638,868
    32 45 33,467,185 13,333,540
    45 53 16,233,536 6,467,544
    53 63 9,788,528 3,899,812
    63 75 5,813,720 2,316,223
    75 90 3,401,258 1,355,083
    90 106 2,029,192 808,443
    106 125 1,239,525 493,835
    125 150 734,672 292,698
    150 180 425,157 169,385
    180 212 253,649 101,055
    212 250 154,941 61,729
    250 300 91,834 36,587
    300 355 54,371 21,662
    355 425 32,196 12,827
    425 500 19,305 7,691
    500 600 11,479 4,573
    600 710 6,796 2,708
    710 850 4,025 1,603
    850 1000 2,413 961
    1180 1400 890 354
    1400 1700 513 204
    1700 2000 302 120
    2000 2360 184 73
    2360 2800 111 44
    2800 3350 66 26

    Note: This table assumes the mean diameter is half way between the upper and lower size.

  • Monodisperse Silica Nanospheres and Microspheres – Dry Powder

    Scientists are always pushing the limits of the technology and looking for more precise products and equipment to enable the next technology. Advances in nanotechnology is what enables this progress.  Nanoparticles are particles that have the dimensions of no less than 1 nanometer and no greater than 1000nanometers (1 micron). Nanospheres are specialized highly spherical nanoparticles. In an effort to provide our customers in the nanotechnology industry with specialty nanomaterials, Cospheric LLC has added a selection of highly precise and spherical monodisperse silica nanospheres to their broad product line and created CosphericNano – a website dedicated exclusively to nanospheres and nanoparticles.

    Silica Microspheres 3.8um DiameterSilica nanoparticles (nanospheres) and silica microspheres are now available in distributions of less than 10% CV in the sizes of 0.25 micron, 0.5 micron, 0.62 micron, 1 micron, 4 micron and 8 micron. Each product is extensively characterized under SEM (scanning electron microscope) to ensure perfect sphericity of each nanosphere and tight particle size specifications.

    Selection of Silica Nanospheres and Nanoparticles are available:

    SIO2MS 0.25um (250nm) <10% CV

    SIO2MS 0.48um (480nm) <10% CV

    SIO2MS 0.62um (620nm) <10% CV

    SIO2MS 1.15um  <10% CV

    SIO2MS 3.8um <10% CV

    SIO2MS 7.8um <10% CV

    SIO2MS 4-6um  (2-19um range)

    Dry precise monodisperse silica nanospheres are frequently used for biotechnology applications, sintering, microfluidics, electronics, optical coatings, spacers and other high tech applications.

  • 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” »