Crystec Technology Trading GmbH

Conveyor furnaces are available for a wide range of applications such as hardening, firing and sintering of thick films, electrodes or discrete electronic components, as well as for processes like annealing, drying or curing of sealants or plastics, soldering, brazing or solder leveling. Special, ultra-clean (particle-reduced) versions are used in the manufacture of flat panel displays. On this page we provide an overview of different designs of conveyor furnaces. These can be operated under air or under protective / inert gases such as nitrogen (N₂) and argon (Ar). However the list below is not a complete list. Please contact us if you would like further information.

Thick film technology is used to manufacture single electronic parts like resistors and capacitors, hybrid circuits, heating elements, sensors and display systems. The substrate materials are ceramics (Al₂O₃, AlN, BeO, ZrO₂), glass, boards, metal substrates with insulating coatings and thermal print heads. Thick-film paste compositions may include low-melting glasses, cermets, polymers or organometallic compounds.

Thick layers are usually applied by screen printing and in some cases structured photolithographically.

The thick‑film pastes contain binders and solvents. In the first processing step the layers are pre-dried to remove solvents. This is followed by a firing step to remove the binder and to achieve the required properties. Two parameters are especially important: the temperature/time profile and the gas flow. The temperature/time profile is prescribed by the paste manufacturer.

Besides many specialized processes, there are standard temperature profiles for firing cermet pastes. Typical processes take between 30 and 60 minutes in total. These profiles often include a temperature plateau at 850°C for about 10 minutes. During the heat-up to 600°C the binder burns out. The region of the furnace where this occurs is called the burnout zone.

The shown MT furnace type is equipped with a highly accurate temperature controller and a muffle designed for excellent gas stability and reproducibility. Atmosphere stability in the furnace chamber is achieved by gas purge chambers at the furnace entrance and exit. A forced extraction with a blow-off nozzle is positioned precisely where needed.

For two‑sided firing of samples they can be fixed on special holders on the metal mesh. Temperatures up to 1400°C are possible.

Metallization Pastes

Metallization pastes are fired depending on the paste at temperatures between 500 and 950°C. Soldering pastes for Cu/Ag eutectics are fired under humid H₂ or cracked ammonia (forming gas) at 800-840°C.

Special Firing for Base-Metal Pastes (Cu Pastes)

Firing copper pastes requires particularly careful gas control due to the sensitivity of the pastes to air. Therefore a nitrogen-purged conveyor furnace must be used for this application. The oxygen concentration should be kept below 5 ppm.

Firing Processes for Glazes

Glazes for resistors are normally fired at 500-600°C (typically at 525°C). The first glaze used in thermal print heads is processed between 850 and 930°C, the corresponding cover glaze at 850°C. Other glazes are also fired between 500 and 930°C.

Cover-Glass Firing

Covering temperatures depend on glass layer thickness, firing time and application. The temperature range for firing is 400-675°C.

Polymer Capacitors, Dielectrics and Protective Coatings

Polymer capacitor layers are often based on silver-containing phenolic resins (curing temperature 80-120°C) or acrylates, which cure at only 80-120°C. Dielectric layers and protective coatings are often based on silicones or epoxy resins and are cured at 125-200°C.

A specialty of Jtekt Thermo Systems (formerly Koyo Thermo Systems) are special versions of conveyor furnaces for ultra‑clean applications and/or high temperatures. Conveyor furnaces can be equipped with quartz muffles and ceramic transport chains. Ceramic chains are available in various sizes and materials.

Transport in this soldering furnace is via a metallic mesh belt. The operating temperature is approximately 260°C. The furnace uses a vertical gas flow and can be operated under nitrogen or reducing atmosphere (forming gas). Emphasis was placed on simple and safe handling.

For lead‑free soldering applications Jtekt developed a special lift‑beam furnace that is particularly low in vibration. Details are available on request.

The small conveyor furnace shown here combines high performance with a favourable price. To keep construction simple and to reduce weight and cost, LGO heating elements are used. The touch-sensitive display enables easy operation. This furnace can be used for many applications, not only in R&D but also for pilot lines and small production lines. It can operate at temperatures from 350°C to 1000°C. The smallest version has dimensions of 530 x 1355 x 3000 mm³ (W x H x L). The conveyor width is 100-200 mm.

Primarily for drying thick paste layers, Jtekt Thermo Systems (formerly Koyo Thermo Systems) developed a conveyor furnace with infrared heating. Temperature uniformity at 130°C is ±5°C.

Jtekt Thermo Systems offers two types of hot‑plate systems. The first version uses Teflon belts for transport, the second uses a shuttle system. In both cases substrates are processed individually. The maximum achievable temperature is 150°C / 200°C.

Roller transport furnaces were developed for annealing large and heavy loads. Transport in these very clean, horizontal continuous furnaces is via driven stainless steel rollers. To avoid metallic contamination of substrates, ceramic tubes made of pure aluminium oxide can be mounted over these steel rollers. All rollers are driven by a special chain system that prevents slippage between the roller and the product being annealed. The actual furnace consists of a special glass muffle and remote‑IR Moldatherm^® heaters. Modern temperature control enables uniformities below 1°C. This furnace can be used for annealing glass panels in plasma display production.

Conveyor furnaces are built from various types of muffles and in most cases from Moldatherm® heating elements. In some cases SiC heaters, IR lamp heaters, convection heaters or hot plates are also used.

The heating elements consist of a special heating wire embedded directly into a ceramic fibre material that serves as external insulation. Moldatherm^® heating elements have particularly low heat capacity. They have properties very similar to the LGO heating elements used in semiconductor furnaces.

The elements ensure easy maintenance of conveyor furnaces. The heaters are compact and light. The furnace is assembled in blocks with Moldatherm^® heaters. Installation is therefore simple and fast. No special tools are required for this work.

Jtekt Thermo Systems employs different transport systems:

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  Wire mesh belt transport (MB type)
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  Metal chain transport (MC type)
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  Ceramic chain transport (CC type)
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  Lift‑beam transport (WB type)
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  Teflon belt transport (TB type)
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  Roller transport (see also PDP process equipment)

We can also customize the furnaces to your specifications in the following areas:

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  manual or automatic loading
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  various loading and unloading systems
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  selection of different process gases such as inert gases, forming gas or hydrogen
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  optional monitoring of oxygen concentration inside the furnace using an oxygen analyzer
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  optional bar control for extended process control and network integration