Apertures / Pinholes / Slots Material Choices:
Molybdenum
- Ladd Research is the world's largest burr-free aperture producer and the majority of our apertures are made of molybdenum. The lifespan of a molybdenum aperture / pinhole is much longer than that of a
platinum aperture. The disadvantage of molybdenum is that it must be cleaned in a vacuum evaporator, usually in a
heated tungsten boat. Platinum / Platinum:Iridium - We offer pure platinum and Pt/Ir for apertures. Standard EM apertures use 90%Pt:10%Ir. The addition of 10% iridium to
platinum adds strength to the material, providing a sharper, cleaner finished product. Platinum apertures are generally cleaned using the Ladd Aperture Cleaning Kit which consists of the Ladd Flamer and accessories. The Ladd platinum tipped tweezers can also be used. The disadvantage to platinum is that it's lifespan is considerably shorter than for molybdenum apertures.
In summary, we would suggest for less expensive disc apertures, you might use Pt/Ir and for the more expensive strip apertures you might choose molybdenum.
Tungsten, Tantalum and Titanium - These materials are used in x-ray devices, pressure related apertures and gas flow apertures such as in the xenon gas propulsion system. They provide added strength and
protection against beam penetration. Gold Foil Apertures - The Ladd gold foil discs are also called self-cleaning apertures due to the extremely thin gold foil and heat.
With the advent of improved EM columns, the need for gold foil apertures has diminished. |
