Types of Sintering Furnaces

When manufacturing electronic ceramics and multilayer ceramic capacitors (MLCC), having the appropriate sintering furnace ensures consistent density, fewer defects and qualified end products. Sintering furnaces heat the green ceramic part so that the particles fuse together, transforming a weak tape into tough, useful parts. With lots of furnace types available, designed for different production volumes and material requirements, the ideal solution matches your production needs while saving costs. Below you’ll find the most commonly-used types of sintering furnaces, how they are used in the manufacture of ceramic/MLCCs, and what buyers need to know.

The Different Types of Sintering Furnaces Ceramic/MLCCs and Their Uses

Not all sintering furnaces are the same, and the following types are common in the manufacture of ceramics/MLCCs:

Belt Sintering Furnace

The belt sintering furnace is mainly used for MLCC production, whereby components walk through a long, multi-zone furnace on a heat-resistant belt. Production is in one continuous feed until the materials have gone through the preheating stage, the sintering stage, and the cooling. This design guarantees that the heat in the MLCCs is on a constant basis, and helps to produce millions of parts every day.

We offer a high-temperature sintering solution for industrial use in this category. Above 600°C, the sintering furnace is a specialized one, designed specifically for MLCC and electronic ceramics with a maximum of 1100°C, a high thermal uniformity (±5°C for the sintering zone), and automated control of the belt’s speed in the production. This guarantees that every MLCC stack in a batch undergoes the same mild densification, and the overall yield of defected parts drops, meaning product reliability in this province is improved.

Batch Sintering Furnace (Box Furnace)

Batch furnaces are packed into smaller footprints, and can thus be appropriate for small-quantity production runs or R&D. Components to be sintered are loaded into a sealed box, the box is brought to the desired sintering temperature, held at that temperature for a predetermined amount of time and then cooled. These furnaces are also useful for testing new ceramic materials, or producing custom ceramic components and MLCCs in low volumes. Though their throughput is less than that of continuous furnaces, batch models still hold their advantages: precise control of temperature and the ability to change how long the furnace is held at temperature for different ceramic materials.

Vacuum Sintering Furnace

For sintered ceramic components whose purity must be tightly controlled or at high risk of contamination from exposure to oxygen, a vacuum sintering furnace is employed. This allows the sintering process to take place in a benign atmosphere free of contamination. An example here would be delicate advanced ceramic substrates for 5G applications. Vacuum furnaces typically find much application in the aerospace sphere or medical ceramic production, though they can also be customized for special MLCC grades when absolutely necessary.

Microwave Sintering Furnace

Rather than relying on external heating elements and hot surfaces, microwave sintering furnaces use electromagnetic radiation to heat ceramic materials from the inside out. This leads to cycles that can be sped up quite considerably, bringing heating time down from hours to mere minutes, while the less aggressive heating input can give a more uniform spread of heat. Emerging in production for large-scale MLCC manufacture, microwave furnaces are gradually becoming popular for lab work and small runs of high-value ceramic components.

How to Select the Right Sintering Furnace?

Choosing the correct furnace depends on volume of production, material type and quality level:

Volume of Production: For large-scale MLCC production (100k+ per day), continuous belt furnaces like our industrial high-temperature product are needed to stay on schedule. A batch type is appropriate for R&D or small custom runs.

Material Requirements: Air exposure leads to oxidation in some materials; these require vacuum furnaces. If the ceramics in question are traditional MLCC types, they go well in continuous or batch air furnaces; on the other hand for new ceramic composites, microwave furnaces are preferable as they lend themselves to making a few first iterations quickly.

Thermal Uniformity: Microelectronics require really tight control of temperature deviations (so that the layers are all uniformly densified). Look for both ±5°C criteria to be met over the entire sintering zone—the industrial continuous furnace in question excels at this, leading to fewer variations in both capacitance and dielectric strength.

Energy Efficiency: Large runs mean that continuous units are generally better for that situation; but even small “micro”-runs are aided by the reduced cycle time obtained through microwave methods; energy use (per unit) is also reduced dramatically.

FAQ

What does a sintering furnace do?

Typically a method for fusing, using high temperatures (typically 850–1600°C), a green-phase ceramic product in order to produce a bond between particles. This has the effect of turning light, sponge-like green ceramic tapes into strong, compact parts that exhibit the physical and dielectric characteristics needed for electronic products including MLCCs.

What are the disadvantages of sintering?

Sintering can be hot work, and in more than one sense. Many sintering processes are extremely energy-hungry. The temperature needs careful control, otherwise warping, very non-uniform densification, etc., can result. Materials that shrink as they are densified will also require care to be taken in pre-sintered component design so that dimensions are kept in containment.

What are the 4 types of furnaces?

In very gross industrial terms, there are four main types: batch furnaces (for small numbers of parts), continuous furnaces (used for big numbers), vacuum furnaces (for materials sensitive to oxidative processes), and induction furnaces, used conventionally for processing metals. For ceramic/MLCC production, we principally employ four types of furnace: continuous belt, batch box, vacuum and microwave sintering furnaces.

What is the fastest sintering furnace?

The fascinating microwave approach to adding sintering has the fastest cycle times, turning out parts in as little as 10–30 minutes. Continuous/length of furnace cycle times with high-speed lines is 4–8 hours. This kind of speed suits rapid prototyping and more specialist materials R&D and small processes. The microwave oven is not, yet, the mainstay of the MLCC maker’s production line.

How much does a sintering furnace for MLCC production cost?

Prices differ on a huge scale of course, depending upon the type of furnace and its size. ‘Batch’ furnaces suitable for laboratory uses start at perhaps $20,000–50,000 and go all the way to the top of the stack industrial continuous belt type priced in wide ranges from perhaps $100,000 to better than a $1 million. Our new and high-temperature continuous version presents manufacturers of MLCCs in the mid-to-large range with a compromise as always of economy and throughput.

Deciding which type of sintering furnace to deploy for the ceramic or MLCC producer is a critical one, determining, not unreasonably, the quality, rate of throughput and cost of production in the longer term. For low-volume makers, ‘research purposes’ runs and so forth, the batch solution is perfect. We offer a similar connection in our continuously running fixed-belt industrial high-temperature box having a predictable and uniform thermal performance also available in 1100°C versions. For low-volume screen manufacturers we can advise you about using other techniques like vacuum/furnace, and microwave. Drop us a line to help you choose the right sintering furnace for your MLCC or ceramic production line.