Thick Film Substrates

Thick Film Substrates are advanced electronic materials used for hybrid microcircuits and integrated electronics, typically made from ceramics, metals, or glass for their electrical insulation, thermal stability, and mechanical strength, with the process involving screen printing conductive patterns, resistors, capacitors, and other passive components onto the substrate followed by high-temperature firing to bond them, creating reliable, highly integrated circuits ideal for applications in automotive, aerospace, and industrial electronics where performance and durability are crucial.

Thick Film Substrates are known for their versatility and durability, making them ideal for applications that require high reliability and excellent thermal performance. Their unique combination of properties, such as resistance to extreme environmental conditions, makes them essential for a wide range of electronic and microelectronic applications. Ceramic materials, such as alumina (Al2O3), aluminum nitride (AlN), and beryllium oxide (BeO), are commonly used because of their superior electrical and thermal conductivity.

Thick Film Substrates also offer significant advantages in terms of integration, as they allow resistors, capacitors, and other circuit components to be directly integrated onto the substrate. This eliminates the need for discrete components, leading to more compact and efficient circuit designs. The integration reduces both the assembly complexity and manufacturing costs, while ensuring that the components maintain optimal electrical, thermal, and mechanical performance over time.

Advantages of Thick Film Substrates :

1, Higher Reliability :
Most commercially packaged semiconductors will have a life span measured in years, while hybrids have a life span measured in decades. and thick film substrates have higher metal interconnection reliability.

2, Wider Temperature Range :
When electronics operate at elevated temperatures the materials used can have a substantial impact on performance and life. With its ability to dispel heat, Thick film substrates performs better and can prevent a device from being damaged by high temperatures.

3, Higher Precision on Resistors :
After thick film resistors are printed, fired and laser trimmed can achieve tolerance +/-1%, or more tighter +/-0.5%.

4, Low Coefficient of Thermal Expansion (CTE) :
Thick Film Substrates has solid and outstanding interatomic bonds, so ceramic hybrid circuits can withstand high temperatures and is still firm, stable, and steady even under changing temperatures.

5, More Compact, Efficient Package, Economical :
Thick Film Substrates can be half the size of a PCB, thick film packaging does not require mounting into a box, an advantage that can be a significant cost savings.

6, Low Failure Rate :
Aside from long term reliability, Ceramic hybrid circuits also exhibit a lower mean time between failure rate when exposed to environmental stresses such as high temperature, mechanical vibration or other harsh conditions.

7, Small Size And Weight :
In applications where a high premium is placed on small size and weight, such as aircraft, missiles, Thick film substrates offer an extremely compact, high performance solution.

8, Excellent Thermal Insulation :
Thick Film Substrate is incredibly insulating; therefore, heat will be less likely to flow through the substrate, preserving the ceramic hybrid circuit's components from getting damaged or harmed.

9, Custom Packaging :
Thick Film Substrates, or custom monolithic IC packages, provide flexibility for shape and package style, as well as the option for improved performance.

10, High Frequency :
High frequency can be handled by a thick film substrate with its dimensional and thermal stability. Industries requiring high-frequency data and electrical signal transmissions.

For more relevant technical introductions, please refer to Thick Film Technology.

Process Features of Thick Film Substrates :

1, Substrates Selection:
Thick Film Substrates are applied onto ceramic substrates, such as alumina (Al2O3), beryllium oxide (BeO), and aluminum nitride (AlN). This ceramic substrate is the base-plate for the hybrid circuits on which the different layers are applied. The ceramic substrate can also be substituted with different types of materials depending on the application requirements.

2, Screen-Printing:
All of the electrical traces (conductive, resistive, dielectric) are formed through a screen-printing process on the ceramic substrate. The screens themselves are produced using either a photomasking technique or laser cutting process. We refer to these screens as "Printed Stencils". In this process, coated regions are selectively hardened by exposure to UV light, followed by an etching process that creates "holes". These holes allow the screen printing machine's squeegee to push the pastes onto the ceramic.

3, Drying and Sintering:
After screen printing thick film substrates onto ceramic materials, they undergo pre-drying in an oven at 200°C and then baking at approximately 850°C. Additional layers are applied through multiple passes of screen printing, followed by drying and baking processes. Other functional elements, such as dielectrics, consist of a combination of glass and specific ceramics. During the firing process, these materials melt and dissolve into each other, resulting in the formation of a new material with specific characteristics.

4, Multilayer Hybrid Circuits Structure:
The additive screen-printing process can be repeated multiple times using dielectric material (protect layer) to insulate the conductor. Additional metal and dielectric layers can be added thus achieving a multilayer structure, It is called "Multilayer Thick Film Substrates". The small openings called vias in the dielectric layers are filled with metal thus connecting various circuit lines to corresponding circuit lines above or below the layer. (Cross-Over Conductors).

5, Through-Hole Metallization:
Thick Film Substrates can utilize various metals for barrel coating and plugging holes drilled through the ceramic substrate. When incorporating metallized through-holes in a design, the opposite side of the board can serve as a separate or interconnected circuit. Utilizing PTH (Plated-Through Hole) with metallization connections allows for the integration of multiple conductor layers, which is highly advantageous in high circuit density requirements.

6, Laser Trimming:
One notable feature of thick film circuits is the ability to print resistors along with other electrical traces. But, resistances printed by the normal process may have a tolerance of about +/-20%. To address this, laser trimming can be employed to reduce variability to better than +/-1%. During laser trimming, each resistor is probed to measure its actual resistance. If the resistance is below the nominal or target value, a laser selectively removes resistive material to reduce the current flow area, increasing the resistance.

7, Inspection Process:
Any defect in the conductive or resistive traces may affect how the final product performs in service and will almost certainly shorten its life. To avoid any defect hybrid circuits in production, every thick film hybrid circuit is inspected under high magnification to find defects before shipping,such as opens, shorts, voids etc.

Why Deed to Customize Thick Film Substrates ?

Custom Thick Film Substrates are often necessary to meet the specific requirements of various applications in the electronics industry. Here are several reasons why customization is not just an option, but a critical aspect of using these substrates:

1. Application-Specific Requirements:
Different electronic applications have unique needs in terms of performance, size, and functionality. Customizing thick film substrates allows manufacturers to tailor the substrate to the exact specifications of the application, ensuring optimal performance and reliability.

2. Improved Thermal Management:
Electronic devices, especially those that operate at high power or high frequency, require efficient thermal management. Custom Thick Film Substrates (Ceramic) can be designed with enhanced thermal conductivity or integrated heat sinks to better manage heat dissipation.

3. Regulatory Compliance:
Electronic devices are subject to various regulatory standards and certifications. Custom thick film substrates can be designed to meet these specific compliance requirements, ensuring that the final product meets all necessary regulations.

4. Miniaturization:
As technology advances, there is a constant drive to reduce the size of electronic components without compromising on their performance. Custom thick film substrates can be designed to fit into smaller form factors, facilitating the miniaturization of devices.

5. Integration of Components:
Custom Thick Film Substrates can be designed to integrate passive components like resistors, capacitors, and inductors directly onto the substrate. This can reduce the overall size of the device, simplify assembly, and improve reliability.

6. Regulatory Compliance:
Electronic devices are subject to various regulatory standards and certifications. Custom Thick Film Substrates can be designed to meet these specific compliance requirements, ensuring that the final product meets all necessary regulations.

7. Environmental Resistance:
Depending on the application environment, substrates may need to withstand harsh conditions such as extreme temperatures, humidity, or corrosive substances. Customization allows for the selection of materials and coatings that provide the necessary environmental resistance.

8. Innovation and Competitive Edge:
Custom Thick Film Substrates can give companies a competitive edge by enabling them to develop innovative products that are not possible with standard, off-the-shelf components.

9. Enhanced Electrical Properties:
Customization enables the creation of substrates with specific electrical properties, such as precise resistance values or improved signal integrity. This is particularly important for high-precision applications like medical equipment or aerospace electronics.

Custom Thick Film Substrates are essential for achieving the highest levels of performance, reliability, and innovation in electronic devices. It enables manufacturers to create products that are perfectly suited to their intended use, providing a competitive advantage in a rapidly evolving market.

Types of Sintering Technology for Thick Film Substrates :

Thick Film Substrates are ceramic materials commonly used in electronic packaging and circuit fabrication. There are two main types based on sintering temperature: High-Temperature Co-fired Ceramic (HTCC) and Low-Temperature Co-fired Ceramic (LTCC). These two technologies differ significantly in terms of material composition, sintering temperature, and applicable ranges, making them suitable for different electronic applications.

1. High-Temperature Co-fired Ceramic (HTCC)
1.1, Overview:
HTCC technology primarily uses high-temperature ceramics (such as alumina, aluminum oxide, etc.) for sintering, with a typical sintering temperature range of 850°C to 1200°C. The key principle of HTCC is to co-fire ceramic substrates with metal electrodes and circuit materials at high temperatures, creating a durable and stable structure capable of withstanding high thermal stress.

1.2, Applications:
HTCC is widely used in microwave circuits, RF components, sensors, electronic packaging, and power circuits. It is particularly valuable in high-frequency electronics, power circuits, and applications requiring high-temperature resistance.

1.3, Characteristics:
● High-temperature resistance: HTCC technology can operate in higher temperature environments, making it suitable for applications in harsh or high-temperature conditions.

● Higher material strength: Due to the use of high-temperature ceramics, HTCC materials have greater structural strength, allowing them to withstand significant mechanical stress.

● Larger substrate sizes: HTCC is suitable for larger circuit substrates and provides good electrical isolation performance.

● Complex processing: Due to the high sintering temperature, the process requires precise control, making it more complex and expensive compared to other technologies.

2. Low-Temperature Co-fired Ceramic (LTCC)
2.1, Overview:
LTCC is a ceramic substrate technology that uses low-temperature sintering materials (such as glass ceramics) to co-fire at temperatures typically below 850°C. The key advantage of LTCC is that it enables metal electrodes and ceramic substrates to be co-fired at lower temperatures, allowing for the integration of high-density circuits.

2.2, Applications:
LTCC is widely used in high-frequency electronics, RF circuits, sensors, IC packaging, and communication devices. It is particularly suitable for applications that require high-density interconnects, miniaturization, and integration, such as wireless communication, sensor modules, and micro-packaging.

2.3, Characteristics:
● Low-temperature sintering: The sintering temperature is lower (usually below 850°C), reducing the risk of oxidation of metals such as gold, silver, and copper that are co-fired with the ceramic.

● High-density integration: LTCC allows for the integration of high-density circuits and multi-layer designs. Multiple circuit layers can be incorporated into a single substrate, making it ideal for miniaturized, complex electronics.

● Excellent electrical properties: LTCC provides outstanding electrical performance, especially for high-frequency applications, with good electrical insulation that helps reduce signal loss.

● Miniaturization suitability: LTCC substrates support multi-layer circuits and small-size designs, ideal for highly integrated, miniaturized devices.

● Lower mechanical strength: Compared to HTCC, LTCC has somewhat lower mechanical strength and may not be suitable for applications requiring large mechanical stress.

High-Temperature Co-fired Ceramic (HTCC) is more suitable for high-temperature environments, applications requiring higher mechanical strength, and larger substrates, such as high-frequency circuits and power electronics.

Low-Temperature Co-fired Ceramic (LTCC) is ideal for small-size, high-density, and multi-layer circuit designs, particularly in applications such as high-frequency communications, sensors, and micro-packaging.

Both technologies have their strengths and are chosen based on specific application needs, including operating conditions, electrical performance, and design complexity.

Comparison of HTCC and LTCC Usd For Thick Film Substrates :

Characteristic:

HTCC (High-Temperature Co-fired Ceramic)

LTCC (Low-Temperature Co-fired Ceramic)

Sintering Temperature:

Higher, typically 850°C to 1200°C

Lower, typically below 850°C

Materials:

Mainly high-temperature ceramics like alumina, aluminum oxide

Mainly glass ceramics, ceramic powders

Applicable Products:

High-frequency electronics, microwave circuits, RF circuits, power circuits

High-density multi-layer circuits, sensor modules, communication devices

High-temperature Resistance:

Excellent, suitable for high-temperature environments

Lower, suitable for standard or low-temperature environments

Electrical Properties:

Good, suitable for high-power circuits

Excellent, suitable for high-frequency circuits and miniaturized designs

Mechanical Strength:

High, can withstand significant mechanical stress

Lower, suitable for low-stress environments

Processing Complexity:

Relatively complex, requires higher sintering temperatures

Simpler, allows multi-layer circuit integration

Substrate Size

Suitable for larger substrates

Suitable for small-sized, highly integrated circuits

Applications of Thick Film Substrates :

Thick Film Substrates are extensively utilized across various industries due to their exceptional properties, such as thermal stability, high reliability, and the ability to withstand harsh conditions. Here are some specific applications of thick film ceramic substrates:

1, Industrial Control Systems: Thick film substrates find applications in industrial control systems, including motor drives, power supplies, and programmable logic controllers (PLCs).

2, Telecommunications: In the telecommunications industry, thick film substrates are used in the production of RFID tags for wireless communication.

3, Consumer Electronics: Thick film substrates are employed in various consumer electronic devices, including smartphones, tablets, and wearables.

4, Energy Systems: Thick film substrates are used in energy systems like solar inverters, wind power converters, and battery management systems.

5, Gas Sensors: For aerospace applications, thick film substrates are used in the development of gas sensors, which are crucial for detecting volatile organic compounds and other gases in the air.

6, Power Electronics: They are also used in power electronics for their ability to handle high power and voltage requirements, making them suitable for use in various power conversion and distribution systems.

7, Aerospace Industry: Ceramic matrix composites (CMCs), which include thick film substrates, are increasingly used in aerospace applications due to their high-temperature resistance, wear resistance, and excellent mechanical properties at high temperatures. Thick film substrates are utilized in components like turbine blades and vanes where cooling technologies, such as film cooling, are crucial for maintaining the safe operation of hot end parts of the engine.

8, Automotive Systems: Thick film substrates are used in automotive systems for engine control modules and other applications where high temperatures and mechanical shock are common. The substrates' ability to dissipate heat and withstand vibrations makes them ideal for these conditions.

9, Medical Sensors: In the medical field, thick film substrates are employed in the development of sensors for monitoring vital signs, including temperature, pressure, and oxygen levels. Their properties make them suitable for use in sensitive medical equipment.

10, Digitally-Driven Hybrid Manufacture: Recent advancements include the development of digitally-driven hybrid manufacturing processes that combine ceramic paste extrusion with sacrificial support printing and micro-machining to produce three-dimensional ceramic green-state parts. This approach allows for the production of precision-engineered ceramic substrates with high densities and minimal shrinkage, suitable for various electronic applications.

Thick Film Substrates are used in the creation of multi-layer circuit boards that are essential for complex electronic devices. These substrates provide the necessary support and insulation for the conductive layers within the circuit boards. These applications highlight the versatility and importance of thick film substrates in modern technology, from enhancing the performance of aerospace engines to improving patient care through medical sensors.

Main Applications of Thick Film Substrates in Automotive Electronics :

Thick Film Substrates play a significant role in automotive electronics due to their ability to withstand harsh environmental conditions, provide thermal management, and integrate multiple components into a compact space. Some key applications of thick film substrates in the automotive industry include:

1, Engine Control Units (ECUs): Thick film substrates are used in the manufacturing of ECUs, which are essential for controlling various engine functions such as fuel injection, throttle valve sensor, Ignition module, ignition timing, and emissions control. The high-temperature stability and reliability of thick film substrates make them suitable for these critical components.

2, Sensors and Actuators: Thick film substrates serve as platforms for fabricating sensors and actuators used in automotive systems. These include temperature sensors, pressure sensors, oxygen sensors (O2 sensors), and various actuation devices that are integrated onto the substrate to monitor and control engine and vehicle functions.

3, Telematics and Infotainment Systems: Thick film substrates are utilized in telematics units and infotainment systems, supporting wireless communication, GPS navigation, voltage regulater, fuel level sensor, entertainment features, and connectivity functions within vehicles.

4, LED Lighting Modules: Automotive lighting systems, including LED headlights and taillights, utilize thick film substrates for mounting LED chips and associated circuitry. These substrates provide a reliable platform for driving and controlling the lighting functions in vehicles.

5, On-Board Diagnostics (OBD): Thick film substrates are integrated into on-board diagnostic systems that monitor and report the performance of various vehicle systems. These systems rely on reliable thick film substrates to ensure accurate data collection and processing.

6, Electronic Control and Monitoring Systems: Thick film substrates are used in various electronic control and monitoring systems within vehicles, such as transmission control units, anti-lock braking systems (ABS), airbag control modules, and vehicle stability control systems. These substrates support the integration of control electronics and sensor interfaces.

7, Power Modules: Thick film substrates are employed in the production of power modules for automotive applications, including motor drive systems, voltage regulators, and power converters. The thermal conductivity and electrical performance of thick film technology are valuable for managing power electronics in vehicles.

Thick Film Substrates contribute to the performance, reliability, and miniaturization of electronic systems in modern automobiles, helping to meet the demanding requirements of the automotive industry for ruggedness, temperature resistance, and long-term functionality.

Design Guidelines of Thick Film Substrates :

We compiled a Thick Film Substrates-Design Guidelines as attached for you to download, It is to better support our customers' needs in designing and applying Thick Film Substrates, This guide covers detailed information on product solutions, engineering design specifications, material properties, available manufacturing processes, and more.

We hope that this guide will assist customers in standardizing their design process while ensuring the manufacturability of the design data, ultimately improving product reliability and production efficiency. Customers are encouraged to refer to the guide when designing Thick Film Substrates to ensure adherence to best practices.

Capabilities of Thick Film Substrates Are As Follows :