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Thick film circuitry sits at the intersection of materials science and high-volume manufacturing.When electronic functionality must be built directly onto a ceramic substrate, thick film circuitry is often the most practical solution. Whether we need patterned conductors, precision resistors, or insulating layers, thick film pastes let us deposit functional materials by printing and convert them into durable films through firing.
Aluminum nitride (AlN) substrates deliver thermal performance that alumina cannot match. That matters in power electronics, RF hardware, and dense assemblies where heat drives reliability.
The catch is that AlN is not a drop-in replacement for alumina in a thick-film process. Surface chemistry, thermal expansion behavior, and firing interactions differ enough that paste selection requires design-level attention rather than simple substitution.
Thick film pastes are engineered suspensions used to build electrical functionality on a substrate. We print the paste (most commonly by screen printing), dry it to remove solvents, then fire it to densify the deposit, bond it to the ceramic, and make it electrically stable.
A typical paste formulation includes:
Because the paste is a composite, performance is rarely determined by a single ingredient. Print resolution, fired microstructure, adhesion, and electrical stability come from how the system behaves as a whole through drying, burnout, sintering, and cool-down.
AlN is chosen when high thermal conductivity is required while maintaining electrical insulation. That combination is hard to obtain from metals, and it is not always adequate in conventional ceramics as heat flux rises.
In practical terms, AlN helps when:
Those benefits are real, but they only translate into hardware if the thick-film stack adheres, remains electrically stable, and withstands the module’s expected temperature profile.
AlN does not behave like alumina at the surface. Alumina is an oxide ceramic, and many thick-film glass systems were historically tuned around oxide bonding.
AlN can form surface oxide under certain conditions, but the surface state can vary with substrate processing, storage, cleaning, and pre-firing steps. That variability can manifest as inconsistent wetting, weaker adhesion, or shifts in the fired microstructure at the interface.
For thick film, that means we treat the AlN surface as a controlled variable. Surface finish, cleaning protocol, and any intentional pre-oxidation or surface conditioning can materially change results.
After firing, the film and substrate cool together. If thermal expansion mismatch is too large, the film can end up in tension or compression, which raises the chance of:
The risk increases with thicker prints, large continuous conductor areas, and aggressive thermal gradients during operation or thermal cycling. Paste systems designed for AlN typically address these stresses through glass selection, particle loading, and fired-film compliance.
Even when the peak temperature is similar to that used for alumina, burnout behavior and interfacial reactions can differ on AlN. If organics do not burn out cleanly, we can trap porosity or residue:
With AlN, consistency comes from treating printing, drying, and firing as a single coupled process rather than independent steps.
When we qualify Thick Film Pastes for AlN Substrates, we focus on a short list of measurable behaviors that connect directly to manufacturing yield and field reliability.
Adhesion is not just a tape test result. We also look at:
If adhesion is marginal, it tends to fail first at corners, narrow traces, and pad edges where stress concentrates.
For conductors, we care about stable sheet resistance, consistent solderability or bondability, and minimal drift after process excursions. For resistor pastes, we care about:
For dielectric layers, we care about insulation resistance, breakdown behavior, and compatibility with adjacent conductors and resistors.
A paste that looks good on a datasheet can still fail the build if it does not print cleanly in your process window. We evaluate:
AlN programs often move fast from prototype to limited production. A paste system that prints reproducibly reduces rework and shortens process development.
We match the paste system to AlN not only for peak performance, but for how the full stack behaves mechanically. That includes conductor-to-dielectric compatibility, resistor encapsulation compatibility, and how the fired films respond to the module’s operating temperature range.
Conductive pastes form traces, pads, and interconnect features. On AlN, the conductor system is often selected around downstream assembly requirements:
In practice, conductor selection also influences the rest of the stack. A conductor’s glass system and firing behavior can affect dielectric adhesion and resistor interactions.
Resistor pastes are used for printed resistors, shunts, sensing elements, and integrated networks. Precision resistors on AlN matter when the module combines power handling with measurement or control.
In our lineup, the FK9600 and FK9900M systems are tailored for AlN substrates. These systems support printed resistor elements, where repeatability and stability are central to the design, and are commonly used when the circuit is close to heat sources or experiences rapid thermal transitions.
Via filling paste exhibits very little sinter shrinkage in order to fill the via as completely as possible. This helps to establish contact between buried and surface mentalizations of multi-layer ceramics.
Encapsulation paste is applied as a protective film onto thick-film resistors of the FK9600 and FK9900M resistor paste series, and onto its contacts. This prevents resistance drifts which could result from environmental factors, such as high air humidity or slight mechanical abrasion.
For AlN, we pay attention to:
The combination of printed functionality and high thermal conductivity makes AlN thick-film circuits relevant across three broad application areas:
AlN substrates are a common fit when power devices generate enough heat that substrate thermal conductivity becomes a limiter. Thick-film layers on AlN can support gate-drive routing, sensing networks, and interconnect features that sit close to the power stage. When modules cycle between load states, the thick-film stack must remain intact while the package undergoes repeated mechanical strain.
RF assemblies can benefit from AlN when heat dissipation and dimensional stability are critical. Thick film conductors are used for patterned features that must maintain geometry, continuity, and electrical consistency under temperature rise and environmental exposure. In certain builds, dielectric layers or protective coatings also contribute to long-term stability.
Printed resistors and conductors on AlN are used in sensor carriers, microheaters, and control elements, where the substrate serves as both a thermal path and a stable platform. In these applications, the resistor’s drift behavior and the conductor’s oxidation or corrosion resistance can drive system performance over time.
At AdValue Technology, we support AlN-based thick-film work in two ways: by stocking paste systems for AlN substrates and by helping teams align paste selection with the realities of their process flow.
As programs move from initial development to repeatable manufacturing, the technical requirements become more specific:
We can support selection across conductor, resistor, and dielectric needs, including the FK9600 and FK9900M resistor systems for AlN, and help map the material choices to your intended firing and assembly path.
Scaling a thick film process on AlN requires more than matching a datasheet to a substrate. It requires paste systems that behave consistently across panels, firing equipment, and production volumes — and technical support that understands where variability hides.
AdValue Technology stocks thick film pastes engineered for AlN substrates and works with teams to build repeatable processes. We help you identify the right materials, resolve process issues, and tighten tolerances as you scale.
Contact AdValue Technology to get the technical support you need to move forward.
