The manufacture of this unique product is covered by US Patent #4163900: Composite electron microscope grid suitable for energy dispersive X-ray analysis, process for producing the same and other micro-components and US Patent #4250127: Production of electron microscope grids and other micro-components.
The SPI Carbon Composite Grid exhibits the typically high Bremsstrahlung background radiation characteristic of low atomic number elements. The grid contains only C, H, N and O and is electrically conductive, especially in the micro-micro amp ranges used in most TEMs and SEMs. The grid itself is very stiff and a bit on the brittle side, but we would not actually want to call it fragile. It is water wettable making possible on-the-grid aqueous treatments. There are some trade-offs, however. In order to derive the benefit of the grid being lower cost than some of the alternatives, one would see a higher Bremsstrahlung background than the beryllium (a disadvantage). The grid is more conductive than carbon-coated-nylon but then again, it is more expensive. The SPI Diamond Grids, laser cut out of diamond wafers, is probably the best solution technically for most users, but it is also the most expensive of the various options.
For certain types of samples, when being studied at high temperatures, the low thermal expansion coefficient of the carbon composite grids might given them particular advantages over the beryllium or even aluminum grid alternatives.
The grids are manufactured it fit comfortably, yet snugly, into a normal TEM grid holder, and the thickness will average about 35 µm. We just can not control the thickness as tightly as we can our other grids and there could be a variation of as much as +/- 10 µm. For special applications, the carbon composite grids can be carefully plasma etched to a thinner dimension and slightly thinner grid bars, something useful for those doing tilting work in their TEM. We apologize for our inability to have tighter control over the thickness of these grids.
We do not recommend exposure of these grids to certain solvents like chloroform because it can cause a curling up of the grids.
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