A blog on the repair, operation and calibration of surface analysis systems and components including electron spectrometers, sputter ion guns and vacuum related hardware. Click on the Index tab below to see a list of all posts. Visit our website at http://www.rbdinstruments.com
Category Archives: General Optics and Vacuum
General information on repair, maintenance, and operation of both PHI (Physical Electronics) and other manufacturers’ systems and components
Our new VB series bakeout packages are an easy way to remove
water vapor from vacuum chambers. The UHV-compatible IRB-600 short wave infrared
radiation emitter mounts on a standard 2.75”/70mm CF flange. The BC-3
controller uses thermocouple feedback to regulate the vacuum chamber
temperature, controls the power to the IRB-600 emitter, and sets the total
bakeout time. These are all the features that you would expect with a vacuum
bakeout package.
What sets the VB series BC-3 apart from other bakeout
controllers is the Vacuum Interlock feature. The Vacuum Interlock uses a
Setpoint relay on your vacuum gauge controller to regulate the vacuum level in
the chamber. For example, if your chamber has ion pumps, you can set your
vacuum gauge controller Setpoint to 4 x 10-6 Torr which will turn
off the heat to the chamber when the vacuum setpoint is reached. Whether your chamber has ion pumps or a turbo
pump, the Vacuum Interlock feature can be used to ensure that your pump does
not get choked with water vapor.
The BC-3 controller can drive two IRB-600 emitters, two heater tapes, or even one of each!
BC-3-Bake-Out-Controller
Infrared radiation(IR) heats the chamber from the inside out and is very effective compared to external radiant bakeout heaters. The thermal conductivity of stainless steel at 100° C is only 15 W/m K compared to 300 W/m K for copper at 100° C. Therefore, it takes a long time for external bakeout heaters to heat up the inside of the vacuum chamber surfaces.
IR heats the internal surfaces of the vacuum chamber very quickly. Using internal IR heat even for a short time during the initial pump-down can have a noticeable effect on pumpdown times and base vacuum. To reach low UHV vacuum levels you need to bake for longer periods of time.
IRB-600 emitter
The short wave IR energy of the IRB-600 emitter drops off as a
function of distance. The internal chamber surfaces that are closer to the
emitter will become hotter than surfaces that are further away from the
emitter. This effect is not precisely linear, but you do need to consider it
with regards to thermocouple sensor placement on the chamber. Typically, the
thermocouple sensor should be about 6-to-10 inches away from the IR-600
emitter. If you have two IRB-600 emitters on your chamber, place the
thermocouple sensor at the midway point between the two emitters.
Once the thermocouple sensor has been placed, you can program
the bakeout temperature setpoint. Typically, the bakeout temperature setpoint
is programed 20° C-to-30° C lower than the temperature on the surfaces that are
nearer to the IRB-600 emitter. If you would like the chamber to be 150° C near
the IRB-600 emitter, program the bakeout temperature to 125° C.
Before using the Vacuum Interlock feature, you need to program
your vacuum gauge setpoint to the desired value. Typically, the vacuum setpoint
is 3 or 4 x10-6 Torr for ion pumps and 5 x 10-4 Torr for
turbo pumps. Then, simply turn the Vacuum Interlock switch on the BC-3
controller to On. If you would prefer to bake the chamber into the turbo pump
before you turn on your vacuum gauge, then set the vacuum interlock switch to
Off; the IRB-600 emitters will turn on and be regulated only by the vacuum
chamber temperature.
In our shop we have a few vacuum chambers that come up to air practically every day, and some days more than once per day. We use the BC-3 with a single IRB-600 emitter and one 600 watt heating tape to effectively remove water vapor. If we know that we will be venting again later in the day, we turn on the BC-3 as soon as we start pumping down the chamber in order to take advantage of viscous flow and to let the turbo pump down the chamber for about 30 minutes. Then we turn off the BC-3 and start the ion pumps; the vacuum chamber will be down in the low 10-8 Torr range within a few hours. If we need a better vacuum, then we bake the chamber out for 8-to-10 hours over night. The following day the vacuum chamber will be in the 10-10 Torr range after the chamber cools down and also using a titanium sublimation pump. Not needing to remove cables and preamplifiers from the chamber is a big time-saver. We use the VB bakeout package practically every day and every time we do, we really appreciate how easy it is to bakeout a vacuum chamber with the BC-3 and IRB-600 compared to external heaters and bakeout blankets.
The BC-3 and IRB-600 are available in 120 VAC and 230 VAC configurations.
For more information on the VB series bakeout controller, visit
our website at this link –
Updated 8-30-19 This post explains the bakeout procedure to improve base vacuum in a PHI 5600 X-ray photoelectron spectrometer. The procedure is basically the same for most of the older PHI (Physical Electronics) Spherical Capacitive Analyzer XPS surface analysis systems. … Continue reading →
This procedure describes how to replace the solenoids in the Auto Valve Controller (AVC) used on Physical Electronics PHI surface analysis systems such as XPS Photo-electron and scanning Auger electron spectrometers.
The AVC provides control of the pneumatic valves on the system by using 24V DC solenoids to route air to either open or close the valves as needed. The symptom for a failed solenoid valve is that the light on the AVC remote box indicates that the valve is open, but the actual valve does not open. Or, it may be that the valve will not close.
The function of each valve is listed below:
V1
Gate valve – Isolates load lock from main vacuum chamber
V2
Vent valve – Isolates nitrogen back-fill from load lock
V3
Isolation valve – Isolates turbo pump from load lock
V4
Differential pumping valve – Isolates turbo pump from ion gun
V5
Vent valve – Isolates nitrogen from turbo pump
V6
Pre-pump valve – Isolates mechanical pump from load lock
There are two ways to test the solenoids;
1. Remove the air line (s) to the suspect pneumatic valve and open/close the valve manually. Some valves have two air lines and some have only one. In the case of two air line valves (typically V1 and V4) air should come out of the top air line to the valve when closed, and the bottom airline on the valve when open. If the AVC remote box indicates that the valve is changing states but the air does not change, then the solenoid is most likely bad.
2. You can remove the P10 cable plug from the back of the AVC measure the 24V DC voltage between the pins for the valve in question as shown in the table below. When ON, you will have 24V DC between the two pins for the solenoid in question.
Before you remove the P10 cable you need to close all valves on the AVC remote (V1, V2, V3 and V4) and turn off the turbo pump (s). Also turn off the air to the AVC manifold on the back of the electronic or vacuum console. Usually the air is connected to the console with a quick connect fitting. See Important Notes before turning off the air.
AVC solenoid wire connector info
IMPORTANT NOTES:
When a solenoid is not working properly it is possible and even likely that the vacuum chamber can come up to air during the solenoid replacement procedure.
It is recommended that all valves be closed and the turbo pump(s) turned off before proceeding with the replacement of a solenoid. Note that even though the AVC remote may indicate that a valve is closed, if the solenoid is defective the valve may not actually be closed.
In addition to turning off the turbo pumps, also turn off the card rack power, all electronics, the ion gauge and the ion pump control.
Finally, before proceeding with the replacement of a solenoid, unplug or turn off the air to the back of the vacuum console. Most valves will hold their state (closed) with no air supplied to the valve, but marginal valves may leak when the air is shut off.
Solenoid replacement procedure:
Close all valves on the AVC
Turn off the turbo pump(s)
Turn off the ion gun, electron gun and X-ray source controllers
Turn off the card rack power
Turn off the DIGIII ion gauge control
Turn off the Boostivac ion pump controller
Turn off the AVC main power
Turn off or unplug the air to the back of the console
Unscrew the front panel AVC screws and slide out the AVC controller a little bit
Unscrew the air manifold screws so that you can access the solenoid screws
Unscrew the solenoid that you want to replace. The V1 solenoid is a little bit higher than the other ones and it is located at one end of the air manifold. Starting with the V1 solenoid, the order is V1, V2, V3, V4, V5 and V6.
Cut the wires to the existing solenoid. Make sure that you have enough length for when you reconnect the wires to the new solenoid. Note that the V1 solenoid has 2 sets of wires, upper coil and lower coil. Make sure that you keep the upper coil label on the wires so that you can connect the new solenoid upper coil wires to the correct set.
Cut the wires on the new solenoid to length and strip the ends on the wires that went to the old solenoid and also on the ends of the new solenoid.
Connect the wires together. White to white, black to black (except for V2 which has a yellow wire). You can use twist connects, in line crimp connectors or solder and heat shrink.
Screw the new solenoid into the manifold. Make sure that the black seals on the solenoid line up with the holes in the manifold. Snug the solenoid down firmly but do not over tighten the screws as the manifold is aluminum and it is easy to strip the manifold.
Use tie wraps to tidy up all the wires
Reattach the air manifold to the AVC controller
Make sure that all of the wires on the back of the AVC controller are still connected properly.
Use the front panel screws to reattach the AVC controller to the console.
Turn on the AVC controller main power. All valves on the AVC remote should indicate closed.
Reconnect the air to the back of the console.
Next, see if the ion pump control starts and stays on in the Run mode. If so, the system is still under vacuum.
Turn on the DIGIII ion gauge control and press the I/T 3 button to turn on the ion gauge.
If the ion pumps started and the ion gauge turned on, you should be back in business and can turn on the turbo pump (s) and use the system as you would normally.
If the ion pump control does not start then the system is up to air or partiality up to air. To test the condition of the vacuum inside the chamber, you can pump on the load lock until you have 5 bars and them manually close V3 and manually open and immediately close V1. That will equalize the vacuum in the load lock with the chamber. Now check how many bars you have on the AVC remote box. If 3 or 4 bars then the chamber is only partial up to air and you can just open V3 and V1 and rough the chamber out for 10 to 15 minutes to get into the 10-6 Torr range and then start the ion pumps.Close V1 once the ion pumps start.
If you only have one bar, then the chamber is likely up to air and you should bring the chamber up all the way by back filling with Nitrogen and then pumping the chamber back down. Those procedures are detailed at the bottom of this blog post.
If you have a leaking solenoid and need a replacement, RBD Instruments provides them and our part numbers are listed below. Please contact us for a quotation.
RBD AVC Solenoid part numbers
Description
RBD part number
AVC solenoid designation
V1 24V Solenoid/Auto Valve Control
T062-4E2RE
V1
V2 24V Solenoid/Auto Valve Control
T062E1-3-10-35RE
V2
V3, V4, V5, V6 24V Solenoid/Auto Valve Control
T062-4E1RE
V3, V4, V5, V6
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Here is where you can buy the old style (cylindrical) AVC solenoids –
If you need to bring the vacuum chamber all the way up to air, here is the procedure –
System up to air procedure
This procedure will allow you to safely bring the 660 scanning auger system up to air for maintenance.
Shut down all electron, ion and X-ray source power supplies.
Turn off the card rack power
If V4 is open, close it by pressing the Diff Pump Ion Gun button on the AVC remote.
Pump the intro. If you need
Turn off the DIGIII ion gauge.
Turn off the Ion pump control and Boostivac control.
Allow the system to cool for at least 30 minutes. (Or just a few minutes if the electron gun was not on.)
Make sure that the turbo pump is on. If you have more than one turbo pump, they both need to be on.
With the turbo pump on and the intro still being pumped, depress the Backfill Chamber button on the Auto Valve control located behind the vacuum console.
You will hear a hissing sound as air is back-filled into the chamber.
Slightly loosen the intro hatch cover so that when the system is pressurized it will open.
Once the system is vented, turn OFF the turbo pump(s).
System Pump Down procedure
This procedure will allow you to safely pump down the system after being up to air for maintenance.
Make sure that all flanges are secured (use new copper gaskets whenever removing and replacing optics on the vacuum chamber).
With the turbo pump(s) off, depress the Rough Chamber button on the Auto Valve control located behind the vacuum console.
Make sure that the intro hatch is closed.
Turn on the turbo pump(s) by depressing the pumping unit button. You will hear the V2 valve close and the V3 and V4 valves open and the turbo(s) will begin to pump the system out.
After about 20 minutes you should have 5 bars on the Auto Valve control remote. Once you have 5 bars, cycle each of the 4 titanium sublimation filaments for about 2 minutes each at 50 amps on the Boostivac control.
Cycle each filament 2 times, with a few minutes of cool down time between filaments.
After all 4 filaments have been out-gassed, make sure that you still have 5 bars on the Auto valve control remote and then turn on the DIGIII by turning the power switch to UHV and depressing the I/T 3 button.
The DIGIII should indicate in the low 10-3 to mid 10-4 range. Allow the turbo to pump until the system pressure is in the low 10-4 to high 10-5 range, about 30 additional minutes.
Cycle the #1 titanium sublimation filament for about 2 minutes at 50 amps. (Note: If a TSP filament can no longer get at least 45 amps, use the next filament).
When the vacuum is in the low 10-5 range, start the ion pump control by turning the Mode switch to Start. Monitor the 10KV scale. The voltage should be increasing (maximum is about 5.5 kV), and the DIGIII should indicate that the vacuum is dropping into the 10-6 range. (Note that the meter on the Boostivac does not always read, if not then just make sure that you are in the 10-6 range and dropping on the ion gauge).
Once the DIGIII indicates the high 10-6 range, close the V1 valve by depressing the Rough Chamber button on the Auto Valve control located behind the vacuum console one more time. You will hear the V1, V3 and V4 valves close.
On the Auto valve control remote, depress the Diff Pump Ion Gun button to differentially pump the ion gun.
The system vacuum will continue to improve over the next few hours. Cycle the #1 titanium sublimation filament every 30 to 45 minutes to help the ion pumps pull the vacuum down.
Once the base pressure is in the low 10-7 to mid 10-8 range, the system can be baked out to obtain the best possible base pressure.
