Thermal Process and Equipment for MLCC Manufacturing:
From Binder Burnout and Co-Firing to Termination Firing

Multilayer ceramic capacitors (MLCCs) are widely used electronic components made by stacking many thin ceramic dielectric layers with internal electrodes. A thin ceramic tape is cast and processed into sheets, and internal electrode patterns are printed on the ceramic layers before stacking; typically followed by lamination, cutting, binder burnout, co-firing, termination, plating, testing, and packaging.

Among these manufacturing steps, thermal processing has a major impact on product quality and production stability. As stated above, "firing" is not a single furnace step. It is usually a sequence of carefully controlled thermal processes. Binder removal, ceramic/electrode co-firing, and termination firing each require different temperature profiles, atmosphere conditions, oxygen levels, possible humidity control, furnace pressure control, gas flow, and furnace designs.

Depending on the material system and production scale, MLCC manufacturers may use box furnaces, belt furnaces, pusher furnaces, or roller hearth furnaces for different firing steps, as indicated by the green sections in the process flow below. Based on the customer's material system and process route, XMZ Technologies can support the major thermal processing steps with Hengli furnace solutions.

MLCC Processing Flow with Highlighted Firing Steps

1. Binder Burnout: First Pre-Firing and Second Pre-Firing

Before MLCC co-firing, binder burnout is used to remove organic materials from the laminated green body in a controlled way. The purpose is not simply to burn off binders, but to control the gas release rate, avoid internal stress concentration, create the pore channels needed for later sintering, and reduce atmosphere disturbance during co-firing.

If a large amount of organic material decomposes in the high-temperature stage, it can make the co-firing atmosphere more difficult to control oxygen pressure and cause fluctuation. A well-controlled burnout process helps reduce carbon residue, protect the internal electrodes and ceramic dielectric system, and prepare the part for stable densification during co-firing.

The goal of binder burnout furnace is to remove these materials gradually under a controlled atmosphere and temperature profile. A stable burnout process helps reduce cracking, delamination, blistering, contamination, and other defects during co-firing.

1.1 Nitrogen Binder Burnout Box / First Pre-Firing Furnace

The first pre-firing step is typically used for low-temperature, slow binder removal. Equipment for this stage can be configured with a stainless-steel chamber, a reflow-like heating method, and automatic pressure control. Depending on the process, the atmosphere may include nitrogen, hydrogen, or water vapor.

For this stage, the design focus is not maximum temperature. The priority is controlled and uniform binder removal, stable furnace pressure, cross-sectional temperature uniformity, and stable atmosphere composition, so that organic can be removed without damaging the ceramic body.

Hengli Automatic Multi-Atmosphere Box Furnace

1.2 Second Pre-Firing Furnace / Secondary Binder Burnout Furnace

The second pre-firing step removes residual organics at a higher temperature after the initial burnout stage. A continuous belt-type furnace can be used for this process. Similar to the first stage, the priority is controlled and uniform binder removal, stable furnace pressure, across-belt temperature uniformity, and stable atmosphere composition.

The furnace can be equipped with FEC heating panels, precise temperature control modules, oxygen and hydrogen monitoring modules, automatic humidification, furnace pressure monitoring, automatic belt tracking, and automatic belt tensioning.

For continuous MLCC production with lower process cost, a belt-type furnace is a mature and practical solution for secondary binder burnout.

Hengli Belt Furnace with Zone-Specific Gas Control

2. Co-Firing / Main Sintering: Pusher Furnace and Roller Hearth Furnace

Co-firing of MLCCs is the main sintering process and one of the most critical firing steps in the production process. The focus is promoting compatible densification and co-firing between the ceramic dielectric and internal electrodes under a stable atmosphere. A well-designed co-firing process helps reduce the risk of cracking, delamination, undesired electrode oxidation or over-reduction, warpage, and dimensional instability.

This stage usually requires a controlled nitrogen-hydrogen atmosphere, and some material systems may also require humidified gas. The equipment design focuses on customized temperature profile and zone layout, gas flow and atmosphere control, furnace pressure stability, atmosphere uniformity, transport stability, and loading configuration.

2.1 Pusher Furnace for MLCC Co-Firing

A long pusher furnace is well suited for stable, high-volume production. The heating zones should be arranged according to the required ramp rate, peak temperature, and soak time. A muffle or flame-isolated chamber design, combined with multi-point heating and closed-loop control at each heating point, helps improve temperature uniformity across the load. The gas system can be designed with multiple gas inlets to support zone-by-zone atmosphere control. Nitrogen, hydrogen, and humidified gases may be blended by section to adjust oxygen content and maintain process stability.

For MLCC co-firing, a pusher furnace is often used when stable high-temperature processing, controlled atmosphere, and consistent loading conditions are required. The design focus includes temperature profile control, atmosphere and oxygen control, furnace pressure stability, pusher movement stability, setter or sagger loading design, and firing uniformity across the load.

A longer pusher furnace can combine secondary binder burnout and sintering. After the first pre-firing step, the product may directly enter the co-firing furnace without a separate second pre-firing furnace, reducing handling steps and potential handling errors.

Hengli MLCC Type Pusher Furnace

2.2 Roller Hearth Furnace for MLCC Co-Firing

For customers focused on higher throughput and shorter firing cycles, a fast-firing roller hearth furnace can be considered. This furnace type is suitable for rapid and continuous sintering with more focus on the transmission accuracy, but it sometime requires the upstream second pre-firing process to be completed before main sintering.

Hengli Roller Hearth Furnace

Pusher Furnace vs. Roller Hearth Furnace: Selection Considerations

3. Termination Firing: Belt Furnace for MLCC End Termination

MLCC termination firing is performed after external electrode paste is applied to both ends of the capacitor body. This step requires stable firing under a controlled atmosphere. The process may require low-oxygen debinding, followed by firing in nitrogen or wet nitrogen.

Hengli can provide belt-type termination furnaces for MLCC end termination. These furnaces use multi-point heating control and lightweight chamber materials to support accurate temperature control and energy efficiency. A dedicated muffle structure and atmosphere system can support high-volume binder removal under high-flow, low-oxygen conditions. The firing section maintains a protective atmosphere for stable termination firing.

The debinding zone can also be designed as a partially removable muffle structure for easier scheduled binder cleaning.

Removable Furnace Chamber Design

Hengli MLCC Termination Firing Furnace

4. Key Capabilities for MLCC Thermal Processing

For MLCC manufacturing, Hengli thermal equipment focuses on four core areas: temperature control, atmosphere control, stable transmission, and process data management.

5. Conclusion

From initial binder burnout and secondary pre-firing to MLCC co-firing and termination firing, HENGLI® can provide a range of thermal processing equipment for MLCC production. Equipment selection can be evaluated together with the material system, process route, production volume, and yield requirements.

Backed by decades of furnace manufacturing experience, only Golden Bridge Award-winning furnace project, and more than 500 furnaces supplied globally in 2025, HENGLI® has built extensive practical knowledge through high-volume, real-world production applications. This scale of deployment has allowed design, process-control, and long-term maintenance challenges to be identified, addressed, and continuously improved across many industries, including MLCC manufacturing.

XMZ Technologies works with customers to review process requirements, compare furnace options, and select equipment suited to the intended production route. For process discussions or equipment selection, contact XMZ Technologies.