Load-lock systems are atmosphere to vacuum sample staging and entry systems
typically mounted to larger research or process systems. They are a convenient and
practical method for transferring samples in and out of vacuum systems. MDC
load-lock systems are available with both circular and rectangular entry ports. Circular port
systems will accommodate sample sizes of 1-3/8", 2-3/8" and 3-3/4" in
diameter. Rectangular port systems will accommodate sample sizes 8" in diameter. All load-lock
systems are comprised of five basic components including a sample staging
chamber, gate valve, sample transporter, quick-access door and an observation
Sample Staging Chambers
Spherical sample staging chambers are constructed with seven vacuum ports, six of
these are arranged in a six-way cross pattern. Four of the seven ports are occupied
by load-lock system components including a circular gate valve, magnetic
transporter, a side mounted quick-access door and an observation
viewport. Two additional ports are used for system pumpdown and venting.
The seventh and final port is blanked off and available for customer disposition.
Rectangular sample staging chambers are constructed with five vacuum ports, four of
which are arranged in a four-way cross pattern. Three of the five ports are occupied
by load-lock system components including a rectangular gate valve, magnetic transporter
and a top mounted quick-access door with an integral observation window. The two
remaining ports are used for system pumpdown and venting.
The stainless steel vacuum gate valves used on load-lock systems incorporate a patented
gate valve locking mechanism. No contact is made between the valve’s body and the
locking mechanism, a feature which markedly decreases vibration and insures
smooth valve operation. Valve low outgassing characteristics can be attributed
to a fusion welded stainless steel body, edge welded stainless steel bellows as well as
small cross-section o-rings and the elimination of blind internal cavities.
The valve’s gate and carriage can be removed through the valve’s bonnet flange
for gate seal replacement, cleaning, etc., without removing the valve body from the
system. MDC gate valves require about half the number of moving parts found in
comparable valves. This reduction in moving components minimizes wear and particulate
generation which in turn provides valves of superior performance and reliability.
Circular load-lock systems are offered with three gate valves sizes 1-1/2, 2-1/2 and 4 inch
port diameters. Standard port mounts are Del-Seal™ CF metal seal flanges, which are
ideal for ultrahigh vacuum systems. Gate valve actuation is manual with
electropneumatic configurations available on request.
Rectangular valves are designed for use in high vacuum applications including
semiconductor processing. Flange-to-flange body thickness is 2.75" (70mm). Load-lock
systems are offered with a slit port 1.00" tall by 8.30" wide. These gate valves are fitted
with manual actuators but can be ordered in electropneumatic configurations.
All load-lock systems are supplied with UHV magnetically coupled sample transporters.
Sample transporters provide manually actuated linear travel and a full 360° sample
rotation, ideal for transporting samples between the sample staging chamber and a
main process chamber.
Linear positioning is controlled by sliding an external sleeve which is magnetically
coupled with the transporter rod and sample holder inside the system. Optional linear
guide rods can be added to circular entry load-lock systems. Rectangular
entry loadlock systems include the guide rod option since rotation of large diameter samples is
not possible on these systems. Guide rods prevent sample rotation during linear
Magnetic transporters come ready to accept the complete range of Cab-Fast® in-vacuum
sample handling accessories. Cab-Fast® sample handlers are specifically designed for
use with the transporters featured in this catalog. Sample holding accessories are not
included with base load-lock systems and must be purchased separately. Reference
page 444 for the complete line of Cab-Fast® sample handling components and
Quick-Access doors provide convenient and fast manual loading of samples in and out of
sample staging chambers. Circular load-lock systems are fitted with blank stainless steel
quick-access doors while the rectangular systems have quick-access doors with
integral glass observation ports. Circular load-lock systems can be fitted with
viewport fitted doors if requested. All access doors are supplied with Viton®
elastomer seals. High temperature Kalrez® elastomers can be used to increase the systems
maximum temperature rating.
Doors are hinged and use a swing-away hand knob locking mechanism. Viewport
fitted doors are constructed with Corning type 7056 glass fused to Kovar® transition
Load-lock system viewports are centered on the sample staging chamber directly above
and perpendicular to the transporter’s axis of motion. They are observation ports that
allow visual monitoring of the sample loading process as well as subsequent sample
rotation during transfer between chambers.
Circular load-lock systems are fitted with flange mounted viewports bolted to the
staging chamber. Rectangular load-lock systems on the other hand have a limited
number of ports and therefore have viewports installed directly to the
quickaccess door. Regardless of the method of installation, all viewports are constructed of
vacuum compatible materials suitable for high and ultrahigh vacuum service. The
viewport windows are manufactured of optical grade Corning type 7056 glass which
is suitable for most vacuum optical applications. These glass viewports are
bakeable to 400°C and limited only by elastomer seals elsewhere in the system.
The 7056 glass is fused to a Kovar® metal sleeve which in turn is fusion welded to a
stainless steel Del-Seal™ CF flange or directly to a quick-access door. The Kovar®
sleeve is a low expansion nickel-iron alloy ideally suited for glass to metal
bonding. It provides flexibility necessary for the survival of the glass seal during thermal excursions.
Care should be taken during the bakeout process of any glass to metal sealed
component. The maximum recommended thermal gradient for glass to metal sealed
components should not exceed 5°C per minute. Thermal gradients in excess of this
can damage the glass to metal seal interface.
Port aligners are adjustable port flange interfaces designed to correct mate-up
between components with alignment
Load-lock gimbals are unique port alignment
instruments specifically designed for the
precision alignment of magnetically coupled
transporters as used with circular and
rectangular entry load-lock systems
presented herein. Load-lock gimbal port
aligners are fitted with precision micrometer
adjustments for both horizontal tilt (above
and below a horizontal plane of travel) and
side to side parallel axial displacement. They
include a stainless steel formed bellows
adapter which mates between the magnetic
transporter and the sample staging chamber.
Other port alignment tools offered in this
catalog include standard gimbals, precision
off-axis and heavy duty off axis port aligners.
Anodized aluminum finishes will begin to discolor when baked in excess of 150°C. This is
only a cosmetic condition which does not impact performance or reliability.
Circular and rectangular entry Load-lock
- Load-lock systems
- Sample staging chamber
- Gate valves
- Magnetic transporters
- Quick-access doors
- Observation Viewports
- Port Aligners
| Port Aligners
|For product listing, features and specifications click on links below
| Load-Lock Gimbal
| Standard Gimbal
| Off-Axis Precision
| Off-Axis Heavy Duty