The HWF hot-wall furnaces offer maximum flexibility and can be used for a wide range of processes – from fine and high vacuum applications to ultra-high vacuum, outgassing, evaporation, or pyrolysis processes. Thanks to full-surface chamber heating, there are virtually no cold spots, ensuring homogeneous temperature distribution and preventing condensation even in demanding applications. Our proven double-axis technology allows precise and reliable process control, even under slight overpressure up to 2 bar absolute.
Technical Data of the M-HWF Series
| Specification | Value Range | Comment |
|---|---|---|
| Maximum temperatures under overpressure | 1000°C | The maximum sample temperature is typically 100°C lower |
| Maximum temperatures under fine vacuum | 1000°C to 400°C | Decreasing for larger HWF models |
| Number of heating zones | 3 to 10 | All HWF furnaces feature a front booster zone. Depending on furnace length, multiple top and bottom heating zones ensure optimal temperature distribution. |
| Useful volume | 10 to 1000 l | For larger volumes, automated loading and unloading systems are available |
| Temperature uniformity within the useful volume | ±5°C | Above 800°C, depending on application |
Applications of the M-HWF Series
| HWF Line | Clean Processes | Contamination-Intensive Outgassing Processes |
|---|---|---|
| Vacuum ranges | Fine vacuum, high vacuum, and ultra-high vacuum | Rough vacuum |
| Inert gases | Ar, N2, He, etc. | Ar, N2, He, etc. |
| Reactive gases | H2, O2, NH3, etc. | H2, O2, NH3, etc. |
| Applications | High vacuum brazing, degassing, vacuum annealing, diffusion annealing, cleaning, sintering processes | Pyrolysis, thermal debinding, contamination outgassing in vacuum, vacuum debinding |
FAQs – Hot-Wall Furnaces
What is a hot-wall furnace?
A hot-wall furnace is a vacuum furnace with a fully heated inner chamber, ensuring uniform temperatures throughout the working area. Mass hot-wall furnaces deliver maximum precision for demanding heat treatment processes such as vacuum annealing, diffusion annealing, high-vacuum brazing, and pyrolysis.
What are hot-wall furnaces used for?
Mass hot-wall furnaces are suitable for a wide range of processes, including: high vacuum brazing, diffusion annealing, vacuum annealing, sintering processes, thermal debinding, pyrolysis, and outgassing. Thanks to their flexibility, they are ideal for research, development, and industrial production.
What are the advantages of a Mass hot-wall furnace?
High temperature uniformity (±5°C within the working volume), flexible vacuum ranges from fine to ultra-high vacuum, prevention of cold spots through full-surface heating, operation under slight overpressure up to 2 bar absolute, and long service life thanks to innovative design and high-quality materials.
Which vacuum ranges do hot-wall furnaces cover?
Mass hot-wall furnaces are available in different configurations covering fine, high, and ultra-high vacuum ranges. They are also suitable for rough vacuum processes and can be operated with inert or reactive gases.
What are the maximum operating temperatures of hot-wall furnaces?
Depending on the model, Mass hot-wall furnaces reach temperatures up to 1000°C – both under overpressure and fine vacuum. The exact temperature depends on the furnace model and process.
Why choose a Mass hot-wall furnace?
Mass hot-wall furnaces combine precision, flexibility, and process versatility. The innovative double-axis technology ensures extremely low leak rates under both underpressure and overpressure conditions – a unique advantage for demanding heat treatment processes in research, development, and production.
Which processes are considered “clean” in hot-wall furnaces?
Clean processes include: high vacuum brazing, degassing, vacuum annealing, diffusion annealing, cleaning, and sintering.
Which processes are contamination-intensive?
Mass hot-wall furnaces can also be used for contamination-intensive outgassing processes such as: pyrolysis, thermal debinding, contamination outgassing in vacuum, and vacuum debinding.
High Vacuum Soldering and Brazing of Ceramics and Metals
Author: T. Ohnweiler
Nowadays many electronic components, for example devices used in satellites or aircraft, have to withstand challenging environments like vacuum or extremely high temperatures. To manufacture such reliable electronic components, a connection between dissimilar materials is required.
Connecting Dissimilar Materials
This connection can be metal-to-metal or even insulator-to-metal. It has to be strong, high temperature resistant, and suitable for use in vacuum, as outgassing of flux material is not acceptable. The purpose of flux material is to remove remaining oxides and to reduce the surface tension in order to promote wetting of the dissimilar materials’ surfaces.
However, if exposed to vacuum or a high temperature environment, the effects of the flux on the electronic component are harmful. The flux material, which contains acid and salts, changes into the gaseous phase due to its high vapor pressure. The resulting condensation of the flux material on the insulators may produce conductive paths causing a leakage current. This process will destroy the expensive component. Unfortunately, the most active (and therefore corrosive) fluxes also form the strongest connections. Some material properties, for example vacuum resistance, cannot be obtained when manufacturing under conventional atmosphere conditions. One other problem with conventional atmospheres is that gas impurities are always embedded in the connecting surface material.
The exact distinction between soldering and brazing is that in the case of soldering (reversible) adhesion is predominant, whereas brazing (irreversible) produces diffusion of the materials, leading to a much stronger connection. The complete process takes place in a high vacuum (HV) or even ultra high vacuum (UHV) environment. These environments prevent oxidation and allow the usage of a solder made of flux-free material. The requirements for components used in vacuum environment are fulfilled.
Ceramic-Metal Bonds
A challenging task is the creation of ceramic-metal bonds. An example of a device consisting of titanium electrodes soldered on a ceramic ring is shown below.
The thermal expansion coefficients of these two materials can possess great differences. The connecting process takes place at temperatures roughly between 800–1200 °C, depending on the filler material. A suitable supporting unit for the ceramic ring and the twelve individual electrodes must be employed. Finding proper settings for reliable production of these devices can be challenging and must be monitored carefully.
To produce such devices, a furnace with special features is required. The furnace needs to be completely sealed to permit heat treatment in a vacuum environment. Depending on the materials and the solder involved, the temperature has to be adjustable up to approximately 1000 °C with reduced leakage, which makes the furnace more quickly available for the next process. This system reduces cycle time and increases efficiency.
The furnace is equipped with a turbo molecular pump in combination with a pre-pump as standard. The vibrations of the pumping system are decoupled from the furnace body. Depending on the required vacuum range, leakage rate is engineered to be at a minimum. For systems equipped with an ultrahigh vacuum (UHV) package, metallic sealing must be used (CF type). The surfaces of all the vacuum components are polished to a perfectly smooth, mirror-like finish. This finish creates a purer atmosphere and a better final vacuum. In the high vacuum range, the number of molecules covering surfaces is much greater than the number of molecules in the vessel itself. Those molecules at the surface affect the vacuum level as they convert to a gaseous phase.
Product Advantages
- Best possible vacuum
- Fast heat up, fast cooling on demand
- Hydrogen partial pressure operation on demand
- Smooth controlled evacuation appropriate for powders
- Vibration-free operation to achieve a bright connection interface free of any distortion
- Data recording for quality management
The heating zones inside the furnace provide superior temperature stability, i.e., a derivation with respect to time smaller than ±1 °C. In vacuum, the heat transfer is only possible by heat radiation (Planck’s radiation law), which yields the best temperature homogeneities, i.e., a temperature gradient in the hot zone of <±10 °C.
Application Example: Electronic Components Used in Satellites
Navigation systems are increasingly used in cars, mobile phones, or other electronic devices. Speed measurement and a positioning accuracy of a few meters are common features of these systems. The data for the Global Positioning System (GPS), on which most navigation systems are based, is provided by satellites. At a height of 20,000 km, the satellites are exposed to vacuum and extremely low temperatures, and the electronic devices which are part of the satellite need to withstand this environment. High vacuum soldering and brazing is the most effective method for producing electronics that meet these demands.
FAQs – Why MASS for High Vacuum Soldering and Brazing
What is high vacuum soldering and brazing?
High vacuum soldering and brazing is a process where dissimilar materials, such as metals and ceramics, are joined in a high vacuum (HV) or ultra-high vacuum (UHV) environment. This prevents oxidation, eliminates outgassing, and allows the use of flux-free solder, resulting in stronger and more reliable joints.
Why choose MASS for soldering and brazing?
MASS provides precise, reliable, and high-temperature resistant soldering and brazing solutions. Our technology ensures maximum process reliability, reproducible results, and superior joint quality for electronics in demanding environments, such as satellites and aerospace applications.
What materials can be connected with MASS processes?
MASS systems can connect metals to metals and ceramics to metals, allowing for complex assemblies. The processes compensate for differences in thermal expansion and produce durable, high-strength bonds.
What are the advantages of MASS high vacuum furnaces?
High vacuum furnaces from MASS offer uniform temperature distribution with high precision (±1°C in critical zones), best possible vacuum levels to prevent oxidation, fast heating and cooling on demand, vibration-free operation for perfect joint interfaces, optional hydrogen partial pressure operation, data recording for quality management, and fully sealed chambers with metallic UHV sealing options.
Which applications benefit most from MASS soldering and brazing?
Our processes are ideal for electronics that must operate in extreme environments, including satellites and space technology, aerospace electronics, high-reliability instrumentation, and components exposed to high temperature or vacuum.
How does MASS ensure quality and reproducibility?
By using high vacuum environments, advanced furnace technology, and precise control over temperature, pressure, and atmosphere, MASS guarantees consistent high-quality results. Every step is monitored and recorded for complete process traceability.
How can I get more information or request a consultation?
For more information or to request a consultation, contact MASS today via email.