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Vacuum technology is the engineering discipline of creating, measuring, and maintaining environments at pressures below atmospheric pressure, then using those environments to do useful work. It applies across a wide pressure range—from rough vacuum near atmospheric down to ultra-high vacuum (UHV)—and its core building blocks are vacuum pumps, chambers, flanges, pressure gauges, valves, and feedthroughs. If you are specifying a system, servicing one, or trying to understand how the parts fit together, the sections below cover what each component does and how they interact.

What "vacuum" actually means

A vacuum is not the absence of everything; it is a space where the pressure and the number of gas molecules per unit volume are reduced relative to the surrounding atmosphere. The practical consequence is that the mean free path of gas molecules increases, and the rate at which surfaces become contaminated by residual gas drops. That is why vacuum matters: it gives you a controlled, low-contamination environment for processes that would otherwise be disrupted by air or moisture.

Vacuum is usually described in ranges rather than a single value, because the equipment and materials that work well at one end of the scale are often unsuitable at the other. Rough and medium vacuum regions are dominated by gas flow behavior, while high and ultra-high vacuum regions are dominated by surface effects and outgassing.

The core components of a vacuum system

A working vacuum system is a chain of components, each of which has to be matched to the pressure range and the process. The main building blocks are:

• Vacuum pumps — remove gas from the chamber. Different pump types cover different pressure ranges, and systems often use more than one in series.
• Vacuum chambers — the enclosed volume where the process or experiment happens. Chamber material, geometry, and surface finish all affect achievable pressure.
• Flanges and components — the standardized connections that join chambers, pumps, and instruments while maintaining a seal.
• Pressure measurement — gauges and residual gas analyzers that tell you what pressure you have actually reached.
• Valves — control the path of gas and isolate sections of the system.
• Feedthroughs and viewports — let you pass power, signals, fluids, or motion into the chamber, or see inside it, without breaking vacuum.

Vacuum pumps

Pumps are usually divided into two functional groups. Roughing or backing pumps (for example rotary vane pumps) move gas from atmospheric pressure down to a moderate vacuum. High-vacuum pumps then take over to reach lower pressures. Because no single pump covers the whole range efficiently, pumps are typically staged. The right choice depends on the target pressure, the gas load, and whether the process produces corrosive or condensable vapors.

Vacuum chambers

The chamber is the stage for the process. It must hold pressure, provide the ports you need, and be clean enough not to release trapped gas. Chamber design also determines how easily you can pump it down and how uniformly you can heat, cool, or coat a sample inside it. Custom chambers are common because process requirements vary widely.

Flanges and components

Flanges are the mechanical interface that makes a vacuum system modular. They must seal reliably and be compatible with the pressure range and bakeout temperatures you intend to use. Choosing the wrong flange standard or seal material is one of the most common sources of leaks and of systems that never reach their target pressure.

Pressure measurement

You cannot maintain a vacuum you cannot measure. Different gauge technologies are sensitive in different pressure ranges, so systems often combine several. Residual gas analyzers go further and tell you what gas is present, which is essential when diagnosing contamination or leaks.

Valves, feedthroughs, and viewports

Valves route gas and isolate regions so you can vent, pump, or service part of a system without disturbing the rest. Feedthroughs and viewports are the interfaces between the vacuum interior and the outside world—carrying electrical power, thermocouples, motion, or optical access while preserving the seal.

How the components work together

The components form a sequence. The chamber defines the volume to be evacuated. A roughing pump reduces the pressure to the point where a high-vacuum pump can operate. The high-vacuum pump continues evacuating while gauges monitor progress. Valves direct the gas path and protect pumps during startup, venting, and servicing. Flanges hold the whole assembly together as a sealed unit, and feedthroughs let the process run inside without opening the system.

The practical implication is that a weak link anywhere in this chain limits the whole system. A perfectly good pump cannot compensate for a leaking flange, a dirty chamber, or a gauge that reads the wrong range.

Vacuum technology vs. PVD, CVD, and ALD

These terms are related but not interchangeable. Vacuum technology is the enabling infrastructure—the pumps, chambers, and hardware that create the low-pressure environment. PVD (physical vapor deposition), CVD (chemical vapor deposition), and ALD (atomic layer deposition) are processes that use that environment to deposit thin films.

In other words, deposition processes are applications that run inside vacuum systems. The vacuum technology determines whether the process can be performed cleanly and reproducibly; the deposition method determines what film is formed and how.

Where vacuum technology is used

Vacuum technology supports both research and manufacturing. Typical settings include:

• Thin-film deposition and semiconductor process research
• Surface science and materials characterization
• Analytical instruments and electron microscopy
• Industrial coating and metallization
• Any process requiring a controlled, low-contamination atmosphere

Because the requirements differ so much between these applications, systems are usually built from modular, matched components rather than a single fixed design.

Practical starting points

If you are new to the field, a useful way to approach it is to work backward from your goal:

1. Define the target pressure and the gases involved.
2. Identify the process (deposition, analysis, coating) and its contamination limits.
3. Select pumps that cover the required range, staged if necessary.
4. Choose a chamber and flange standard compatible with your pressure and temperature.
5. Add measurement, valves, and feedthroughs to monitor and control the system.

Suppliers such as Kurt J. Lesker Company organize their catalog around exactly these categories—vacuum pumps, flanges and components, pressure measurement, valves, feedthroughs and viewports, and complete systems—which makes them a reasonable reference point when mapping out a build.

Vacuum science is the study of how gases behave at pressures below atmospheric and how that behavior dictates the hardware you need. It matters whenever you specify a pump, choose a flange, or pick a chamber material: the pressure regime you're working in determines which components will actually hold vacuum and which will leak, outgas, or fail to reach target. If you're building or maintaining a system for PVD, ALD, CVD, or any process requiring controlled low pressure, the principles below are the ones that drive your component choices.

The pressure regimes and what they demand

Vacuum isn't one condition — it's a range, and each band changes which physics dominates and which hardware is appropriate.

The transitions aren't arbitrary. They mark where the mean free path of gas molecules grows large enough that molecules collide with chamber walls more often than with each other — which is why pumping, sealing, and material choices all shift at these boundaries.

Key concepts that decide your design

Mean free path

The average distance a molecule travels before colliding with another. At atmospheric pressure it's nanometers; in high vacuum it can be meters. Once mean free path exceeds your chamber dimensions, you're in molecular flow, and a pump's ability to "pull" gas depends on how many molecules happen to wander into its inlet rather than on bulk flow. This is why high-vacuum pumps are placed close to the chamber and why conductance — not just pumping speed — governs performance.

Outgassing

Gas trapped in or adsorbed onto chamber walls, seals, and components is released slowly under vacuum. In high and ultra-high vacuum, outgassing often sets the floor on achievable pressure: you can have a perfect pump and still never reach target because the walls are feeding gas back in. Practical consequences include choosing low-outgassing materials, minimizing internal surface area, and baking the system to drive off adsorbed species.

Conductance

The ease with which gas flows through a tube, aperture, or component. A narrow or long path has low conductance and throttles your effective pumping speed at the chamber, even if the pump itself is fast. This is why short, wide pumping lines matter, and why a valve or bend in the wrong place can quietly limit your base pressure.

How the principles translate into component choices

• Pumps: Roughing pumps handle the viscous-flow regime; high-vacuum pumps (turbomolecular, diffusion) take over once molecular flow begins. The two are usually staged, not interchangeable.
• Flanges: Elastomer-sealed flanges (e.g., KF-style) suit rough and some high-vacuum work; all-metal knife-edge flanges are used where bakeout and lower outgassing are required for UHV.
• Materials: Stainless steel is common for chambers because of its relatively low outgassing and bakeability; elastomers, plastics, and certain lubricants can dominate outgassing if used carelessly.
• Feedthroughs and viewports: These are frequent leak and outgassing paths, so their seals and materials must match the target regime.

Kurt J. Lesker Company organizes its catalog around exactly these categories — vacuum pumps, flanges and components, feedthroughs and viewports, pressure measurement, and valves — which reflects how vacuum science maps onto purchasable parts.

Where this shows up in real processes

PVD, ALD, and CVD all depend on controlling pressure and gas composition at the substrate:

• PVD (physical vapor deposition): Material is vaporized and travels to the substrate. Mean free path matters — too much residual gas scatters the vapor before it arrives, degrading film quality.
• ALD (atomic layer deposition): Relies on sequential, self-limiting surface reactions. Residual gas and outgassing can interfere with precursor dosing and purge steps, so base pressure and leak integrity are critical.
• CVD (chemical vapor deposition): Gas-phase precursors react at the surface. Here both pressure control and clean chamber conditions affect film uniformity and purity.

In each case, the same underlying variables — outgassing rate, conductance, and mean free path — determine whether the process works.

Practical consequences of getting it wrong

• Chasing base pressure with a bigger pump when the real limit is outgassing or a virtual leak wastes money and won't fix the problem.
• Using elastomer seals in a UHV application introduces a persistent outgassing source that bakeout may not fully overcome.
• Long, narrow pumping lines reduce effective pumping speed at the chamber regardless of pump rating.
• Skipping leak detection means a small real leak can be mistaken for outgassing, leading to the wrong corrective action.

The general rule: diagnose whether your limit is pumping speed, conductance, outgassing, or a real leak before changing hardware. Each has a different fix.

Where to go next

If you're specifying components, start from your target pressure regime and work outward: it tells you which pump class, flange type, and materials are viable. Kurt J. Lesker Company's product divisions — vacuum products, materials, process equipment, and manufacturing — are organized to support that progression from principle to part, and their site offers a product portfolio, quotation request, and ordering path for moving from specification to purchase.

A vacuum pump is a device that removes gas molecules from a sealed volume to create and maintain a pressure below atmospheric. Choosing the right type comes down to four things: the base pressure you need, the pumping speed required for your gas load, the gases you're handling, and how much contamination or maintenance you can tolerate. Roughing pumps (rotary vane, scroll, diaphragm) cover the range from atmosphere down to roughly 10⁻³ mbar; high-vacuum pumps (turbomolecular, diffusion, cryogenic) take over below that and almost always need a backing pump behind them. This guide explains how each family works and how to match one to your system.

The pressure ranges a pump must cover

Vacuum work is usually divided into regimes, and no single pump spans all of them efficiently:

The practical consequence: high-vacuum pumps cannot exhaust directly to atmosphere. They compress gas from a low inlet pressure to a higher outlet pressure, and that outlet must itself be pumped by a roughing or backing pump. This is why pumps are almost always staged.

The main pump families

Roughing pumps (backing pumps)

These start a system from atmospheric pressure and hold the exhaust side of a high-vacuum pump.

• Rotary vane pumps — oil-sealed, widely used, reach roughly 10⁻³ mbar. Oil lubricates and seals the vanes, but oil can backstream into the chamber if not trapped. Good general-purpose choice for many PVD and coating systems.
• Dry scroll pumps — oil-free, clean, quiet, reach roughly 10⁻² mbar. Preferred where hydrocarbon contamination matters, such as semiconductor or analytical applications.
• Diaphragm pumps — oil-free and compact, typically used as backing for smaller turbopumps or as roughing for clean, low-throughput systems.

High-vacuum pumps

• Turbomolecular pumps — spinning rotor blades impart momentum to gas molecules, reaching 10⁻⁷ mbar and below. Clean, fast to start, but require a backing pump and tolerate only limited particulate or corrosive gas unless specially configured.
• Diffusion pumps — use a boiling oil jet to direct gas downward to a backing pump. Robust and inexpensive for high throughput, but oil backstreaming is a real concern and they need careful warm-up and cooling.
• Cryogenic pumps — capture gas by condensing or adsorbing it on cold surfaces (typically ~10–20 K). Very clean and fast for high and ultra-high vacuum, but they are capture pumps: they must be regenerated periodically and cannot pump certain gases indefinitely.

How pumps are staged in a real system

A typical high-vacuum system works in two stages:

1. Roughing phase — the roughing pump pulls the chamber from atmosphere down to a pressure where the high-vacuum pump can operate (often ~10⁻² to 10⁻³ mbar).
2. High-vacuum phase — a valve isolates the roughing pump from the chamber and connects it as the backing pump for the turbopump, diffusion pump, or cryopump, which then pulls the chamber to base pressure.

The roughing pump therefore does double duty: it evacuates the chamber initially, then continuously removes the gas the high-vacuum pump compresses and expels. If the backing pump is undersized or fails, the high-vacuum pump loses its compression ratio and base pressure suffers.

Selection criteria

Work through these in order — each one narrows the field:

• Target base pressure. If you only need rough vacuum (e.g., for load-lock or backing duty), a rotary vane or dry pump is enough. For high or ultra-high vacuum, you need a high-vacuum pump plus a suitable backing pump.
• Pumping speed at the operating pressure. Pumping speed is not constant across the pressure range; check the manufacturer's speed-vs-pressure curve, not just the peak number. Match speed to your gas load (outgassing, process gas flow, leaks).
• Gas load and gas type. Heavy gases, hydrogen, and corrosive or condensable gases behave differently. Hydrogen is hard for diffusion and cryo pumps; corrosive gases demand corrosion-resistant materials and appropriate purge or trap arrangements.
• Contamination tolerance. If hydrocarbon or oil contamination would ruin your process, choose dry (scroll/diaphragm) roughing and a turbopump rather than oil-sealed rotary vane or diffusion pumps.
• Maintenance and duty cycle. Oil-sealed pumps need oil changes and filter service; dry pumps avoid oil but have tip-seal wear; cryopumps need regeneration. Match the maintenance burden to your uptime requirements.

Common failure points and troubleshooting

• Oil backstreaming — oil vapor migrates from a rotary vane or diffusion pump into the chamber. Symptoms include rising base pressure and contamination. Fixes: use a cold trap or foreline trap, or switch to dry pumps.
• Seal and vane wear — rotary vane pumps lose ultimate pressure as vanes and seals wear. A pump that once reached 10⁻³ mbar but now stalls higher often needs a rebuild.
• Loss of ultimate pressure — usually not the pump alone. Check for leaks, outgassing from chamber materials, a saturated trap, or a backing pump that can no longer reach its required foreline pressure.
• Cryopump saturation — capacity for a given gas is finite; base pressure rises as the cold surfaces load up, signaling time to regenerate.
• Turbopump backing loss — if the backing pump fails or the foreline valve is mis-set, the turbopump can overheat or lose compression. Interlocks and foreline pressure monitoring protect against this.

Where to source pumps and support

Kurt J. Lesker Company supplies vacuum pumps alongside flanges, feedthroughs, valves, traps, fluids, and leak detectors, and offers pump repair and service. If you're specifying a complete system, the pump choice should be made together with the chamber, flanges, and pressure measurement so the stages match. You can browse the vacuum pump portfolio, request a quotation, or place an order through their site; regional sites are available for the US, Europe, UK, India, China, Japan, South Korea, and other regions.

A vacuum flange is the standardized mechanical joint that connects two vacuum components—tubes, chambers, pumps, valves, or feedthroughs—while maintaining a sealed environment. Choosing the right type means matching three things at once: the flange standard (KF, ISO-K/ISO-F, or CF), the seal material (elastomer vs. metal), and the size and bolt pattern so mating parts physically fit. Get all three right and you have a demountable, leak-tight connection you can open and reseal repeatedly.

What a Vacuum Flange Actually Does

Every vacuum system is assembled from separate parts, and flanges are where those parts meet. A flange must:

• Seal against atmosphere so gas doesn't leak in (or out, for over-pressure systems).
• Locate components precisely so bores align and flow paths stay continuous.
• Allow disassembly so you can clean, replace, or reconfigure parts without cutting and re-welding.

Kurt J. Lesker Company (KJLC) lists "Vacuum Flanges & Components" as a core product category alongside pumps, valves, and pressure measurement—flanges are the connective tissue that ties those categories into a working system.

The Three Main Flange Standards

Most vacuum work uses one of three families. They differ mainly in how they seal and how much vacuum (and heat) they tolerate.

KF flanges

Small, quick to assemble with a single clamp or chain clamp. Best for forelines, roughing lines, and anywhere you need to break the connection often. The elastomer O-ring sets the practical temperature and vacuum ceiling.

ISO-K and ISO-F flanges

Used for larger-diameter connections. ISO-K uses claw clamps around the outside; ISO-F uses bolts through a fixed bolt pattern. Same sealing principle (centering ring with O-ring), so choose based on whether you want fast clamping (K) or a more rigid bolted joint (F).

CF flanges

The knife edge on each flange bites into a soft copper gasket, creating an all-metal seal. This is what you use for UHV and for systems that get baked to drive off water and other adsorbed gases. The trade-off: copper gaskets are typically single-use, and assembly needs even, sequential bolt tightening.

How to Match Flanges Between Components

Mating parts must agree on all of these, or they won't seal:

1. Standard — a KF part will not bolt to a CF part. Adapters exist, but each adapter adds a joint and a potential leak path.
2. Nominal size — e.g., KF-25, ISO-63, CF-35 (the number refers to the nominal bore, not the outer diameter).
3. Bolt/clamp pattern — ISO-F and CF have fixed hole counts and spacing; ISO-K and KF use clamps sized to the flange.
4. Seal interface — the centering ring or gasket must match the flange face geometry.

A practical rule: stay within one standard for a given section of the system, and use a single adapter only where you must transition (for example, CF at the chamber, KF at the roughing pump).

Metal vs. Elastomer Seals: When Each Is Appropriate

• Elastomer (Viton®, Buna-N, silicone): convenient, reusable, lower cost, good for rough and high vacuum. Choose when you don't need UHV or high-temperature bakeout.
• Metal (copper, sometimes aluminum): required for UHV and bakeout. Choose when residual gas levels matter—deposition, surface science, or any process sensitive to water and hydrocarbon background.

If your process involves PVD, ALD, or CVD (all listed in KJLC's application areas), the chamber side is often CF precisely because those processes demand clean, bakeable, low-outgassing joints.

Common Causes of Flange Leaks and How to Check Them

Most flange leaks trace back to a few fixable mistakes:

• Dirty or scratched sealing surfaces — a fingerprint or a nick across a knife edge defeats the seal.
• Damaged or reused gasket — copper CF gaskets are generally single-use; a deformed O-ring won't reseat.
• Uneven bolt torque — tighten in a star/cross pattern in stages, not one bolt fully at a time.
• Wrong or missing centering ring on KF/ISO joints.
• Mismatched standard or size forced together.

To check: isolate the suspect joint and use a helium leak detector, or perform a simple pressure-rise (rate-of-rise) test on the isolated section. Spraying a volatile liquid at a joint while watching a gauge or RGA can localize a leak, but helium detection is the more definitive method for small leaks.

Making the Choice

• Roughing/foreline, frequent assembly: KF with elastomer seals.
• Larger high-vacuum connections: ISO-K (fast clamping) or ISO-F (rigid bolted).
• UHV or bakeout, clean processes: CF with copper gaskets.
• Transitioning between standards: use one purpose-built adapter, and keep the rest of the run consistent.

KJLC's product portfolio covers flanges and components across these standards, and the site offers a quotation path if you need help specifying a custom chamber or matching a full assembly.

A vacuum system is the integrated assembly of a chamber, a staged pumping train, pressure measurement, and control hardware that together hold a process environment at a target pressure. It is not a single product you buy off a shelf — it is a matched set of components, and its performance ceiling is set by the weakest interface between them. This explanation is for anyone specifying, assembling, or troubleshooting a system for a process such as PVD, ALD, CVD, or sample manipulation, and it focuses on how the parts constrain each other rather than on any one component in isolation.

The four functional blocks

Every working system, from a small bench rig to a production deposition tool, contains the same four functions. They can be spread across many parts or combined, but none can be missing.

The chamber is where the process happens, but it also sets the gas load: surface area, outgassing from materials, and the number and type of feedthroughs all determine how much gas the pumps must remove. A chamber that is large, has many ports, or uses high-outgassing materials will demand more pumping than a small, simple one at the same target pressure.

Why pumping is staged

A single pump rarely covers the whole range from atmosphere to high vacuum. Instead, systems use a two-stage approach:

1. Roughing (backing) pump — for example a rotary vane pump — takes the chamber from atmosphere down to a low-vacuum range.
2. High-vacuum pump — such as a turbomolecular pump — takes over from there and reaches the base pressure the process needs.

The reason is mechanical. High-vacuum pumps cannot exhaust directly to atmosphere; they need a low-pressure foreline to operate. The roughing pump provides that foreline, and the two run in series. This is why the roughing pump's speed and ultimate pressure matter even though it never touches the high-vacuum regime directly — it sets the floor the high-vacuum pump works against.

A practical consequence: if the foreline is restricted or the roughing pump is undersized, the high-vacuum pump loses compression ratio and the base pressure suffers, even if the high-vacuum pump itself is fine.

How flanges, feedthroughs, and valves set the ceiling

These components are where most real-world systems fall short of their theoretical pressure, because each one is a potential leak path or a conductance bottleneck.

• Flanges determine leak-tightness and, through their bore, how freely gas flows to the pump. A small-bore flange on a high-throughput line chokes conductance.
• Feedthroughs bring power, gas, motion, or signals into the chamber. Each one is a sealed penetration, and each adds surface area and potential virtual leaks.
• Valves isolate sections, switch between pumps, and throttle flow. Their placement decides whether you can pump one region while venting another.

A useful way to think about it: the pumps set how fast you can remove gas, but the flanges, feedthroughs, and valves set how much gas can reach them and how well the volume stays sealed. A system with excellent pumps and poor conductance will still be slow and may never hit its target base pressure.

Closing the loop with measurement and control

Measurement and control turn a collection of parts into a system that holds a setpoint.

• Pressure measurement spans several decades, so systems typically use more than one gauge type, each suited to a range. A gauge that is accurate at low vacuum may be useless at high vacuum, and vice versa.
• Residual gas analyzers go further and report which gases are present, which is how you distinguish a real leak from outgassing or a contaminated chamber.
• Control sequences the valves and pumps so that, for example, the high-vacuum pump is not exposed to atmosphere, and it regulates pressure during a process where gas is flowing.

Without measurement you cannot verify the target pressure; without control you cannot repeat it run to run.

How the application shapes the design

The process family changes which block dominates the design:

• PVD and sputtering — often need low base pressure and good conductance for process gas flow; chamber geometry and target placement matter.
• ALD and CVD — involve continuous gas flow and often corrosive or reactive precursors, so pumping choice and materials compatibility move to the front.
• Sample manipulation — motion feedthroughs and load-lock arrangements become the design driver, since samples must move without breaking vacuum.

In each case the same four blocks are present, but the relative importance of base pressure, gas throughput, corrosion resistance, and mechanical access shifts.

Practical selection inputs

To decide whether a system will meet a requirement, gather these inputs before choosing components:

• Target pressure — the base pressure and the operating pressure during process, which may differ.
• Gas load — outgassing from chamber and fixtures plus any intentional process gas flow.
• Chamber size and geometry — volume, surface area, and port layout, which affect both gas load and conductance.
• Process compatibility — whether the gases, temperatures, and materials involved require specific pump types, seals, or corrosion-resistant construction.

Matching these four inputs against the pumping train, the flange and feedthrough choices, and the measurement range is what determines whether a system works. A component that is excellent in isolation can still be the limiting factor once it is installed in the assembly.

Kurt J. Lesker Company describes itself as a manufacturer and distributor of vacuum products and systems, offering items such as customized chambers and rotary vane vacuum pumps, and provides paths to view a product portfolio, start a quotation, or place an order. For a specific build, those are the practical next steps once the four inputs above are defined.