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Real Time Sensor for Localized Pressure in E Beam Machining

IP.com Disclosure Number: IPCOM000087399D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Spector, CJ: AUTHOR

Abstract

Machining by electron beam 10 (E-beam) has been used to provide holes or vias 12 through multilayer ceramic 14. Intense heat is generated by the conversion of the electron potential energy to kinetic energy and then to thermal energy by impacting the beam 10 on a carefully focused spot. The energy density is such that some of the target area is volatilized. The minimum size of the machined spot is controlled by, among other factors, control of focus of the beam 10. Vaporized material leaving the machined area obstructs the beam and is ionized by the beam creating a local plasma 16, which in turn defocuses the beam 10. The beam can be refocused by a change in focusing coil 18 current to a level appropriate to the plasma intensity (density) in the path of the beam.

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Real Time Sensor for Localized Pressure in E Beam Machining

Machining by electron beam 10 (E-beam) has been used to provide holes or vias 12 through multilayer ceramic 14. Intense heat is generated by the conversion of the electron potential energy to kinetic energy and then to thermal energy by impacting the beam 10 on a carefully focused spot. The energy density is such that some of the target area is volatilized. The minimum size of the machined spot is controlled by, among other factors, control of focus of the beam 10. Vaporized material leaving the machined area obstructs the beam and is ionized by the beam creating a local plasma 16, which in turn defocuses the beam 10. The beam can be refocused by a change in focusing coil 18 current to a level appropriate to the plasma intensity (density) in the path of the beam.

The operation depends on the fact that plasma 16 is luminous in proportion to local pressure. Therefore, a light detector 20 for measurement of the light given off by the interaction of the electron beam and the local gas can be used as a direct, real-time sensor of the perturbing field that the beam sees at its critical point. The information derived from the sensor 20 is applied to a correction circuit 22 and the electron beam is kept in good focus regardless of the cutting time or rate. The figure shows the E-beam 10 and the focus control arrangement 22 operative from the light detected from the luminous plasma 16.

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