New Materials and Proprietary Processes, for producing high performance field emission cathodes, makes VEC Imaging the World Leader in developing nanotube based multi-beam x-ray (MBX) tubes
VEC Imaging Replaces the traditional coiled filament with nanotube (NT) field emission emitter (Cold Cathode)
Immediate benefits are recognized from this revolutionary change:
- Chemically and mechanically very stable
- Optimal emission characteristics (low turn-on electric field, high emission current)
- Cold cathode with no heat generation (high energy efficiency)
- Ultra fast switching on / off
- Cost-effective manufacturing
Innovative NT Materials
Moving beyond today’s CNT based emission cathodes, we have developed Compound NT containing more than one element. Compared to pure CNT, our compound NT has:
- improved chemical and thermal stability
- better electrical and thermal conductivity
- enhanced field emission properties (high emission current and higher emission stability).
New Cathode/Emitter Activation Process
VEC Imaging has taken the cathode activation process to the next level. Our new process is based on curable liquid adhesives, instead of rigid adhesive tape. Our process does not have the issue of being highly sensitive to process parameters that are difficult to control, such as the adhesive strength and applied pressure. Instead we can control the activation results with high accuracy by controlling easily controllable process parameters curing temperature and time.
New Cathode/Emitter Deposition Process
VEC Imaging has developed and patented a Paste and Screen Printing (SP) process for making NT cathodes with high accuracy. This process overcomes critical technical difficulties resulting from the chemical vapor deposition (CVD) direct growth and electrophoretic deposition (EPD) process used today in terms of control, consistency and reproducibility, we have achieved:
- excellent reliability and consistency on mass production scale
- extremely accurate control of average film thickness (± 1.5 µm) within one cathode and among different cathodes
- much more uniform and smooth cathode surface (surface roughness ± 3 µm)
- improved production yield and reduced material and production costs
Additional Proprietary Innovations
- Electrical connection to the NT emitter uses a one step wire bonding process, instead of the high temperature brazing process, which simplifies manufacturing process and reduces production cost.
- An unique gate and cathode design improves the accuracy of the gap distance between the gate and NT emitters.
- Gate potential can be individually controlled and biased positively and also negatively while modulate NT emitter potential at the same time to always maintain a positive electric field between the gate electrode and NT emitters, which provides improved protection of the NT emitters from ion back bombardment.
- Tungsten gate mesh is made by a dry laser cutting process, an environmentally green process with improved accuracy (mesh bar and mesh opening dimension tolerance of ± 5 µm for laser cutting vs ± 20 µm for the standard etching process.