Thick Film Hybrid Circuits

Thick Film Hybrid Circuits are highly reliable electronic circuits made by combining thick-film technology with ceramic substrates, involving the printing of conductive, resistive, precious metal, or insulating pastes onto alumina or aluminum nitride substrates, followed by processes like high-temperature sintering, laser trimming, photolithography, and bonding encapsulation, which integrate specific components such as resistors, capacitors, sensors, or heaters, widely applied in automotive, aerospace, medical, and telecommunications industries, offering advantages in customizability, and high power handling.

Thick Film Hybrid Circuits enables the creation of resistors, capacitors, conductive traces, and other passive components directly on the ceramic substrate, eliminating the need for separate discrete components. These conductive elements need be fired in tightly monitored temperature controlled, multi-zoned furnaces, binding the conductive paste to the base material and becoming an integral part of the thick film hybrid circuits.

Thick Film Hybrid Circuits are known for their stability and durability, making them suitable for various operating conditions and environments. The thick film material provides good adhesion to the substrate and exhibits excellent resistance to temperature variations, humidity, and mechanical stress. Hybrid Circuits offers several advantages, including cost-effectiveness, compactness, and good electrical performance.

Main Features of Thick Film Hybrid Circuits :

1, Versatile Applications: Thick Film Hybrid Circuits find applications in various industries, including commercial, industrial, scientific, and military sectors, due to their adaptability and reliability.

2, Temperature Stability: Thick Film Hybrid Circuits exhibit excellent temperature stability, typically around 100ppm/°C, ensuring reliable performance across varying temperatures.

3, Multi-layer Integration: The multi-layer thick film technique allows for enhanced integration by using screen printed insulating dielectrics, providing connections between layers only where necessary.

4, Increased Reliability: Thick Film Hybrids offer improved reliability due to the use of robust ceramic substrates and high-temperature sintering processes.

5, Low Weight: The use of ceramic substrates results in lightweight circuits, making them suitable for applications where weight reduction is important.

6, Circuit Miniaturization: Thick Film Hybrid Circuits allow for compact and space-saving circuit designs, enabling miniaturization in electronic systems.

7, Low Cost: Thick Film Hybrid Circuits provide a cost-effective alternative to traditional PCBs, with reduced component count, lower assembly costs, and quicker assembly/test times.

8, Ceramic Substrates: The use of ceramic substrates in Thick Film Hybrid Circuits enables efficient heat dissipation, resulting in cooler running circuits.

9, Laser Trimmable Resistors: Thick Film Hybrid Circuits offer the ability to laser trim resistors with high tolerance conditions, enabling precise resistor values for different applications on the same board.

10, Integration of Components: Thick Film Hybrid Circuits allow for the integration of resistors, capacitors, conductors, semiconductors, and interchangeable conductors on ceramic boards, offering increased package density and reliability.

Please refer to Thick Film Technology for more informations.

Advantages of Thick Film Hybrid Circuits :

1, High Thermal Conductivity Applications: When electronics operate at elevated temperatures, the materials used can have a substantial impact on performance and lifespan. Ceramic substrates have the ability to dissipate heat better, preventing devices from being damaged by high temperatures. Depending on the material used, such as Alumina or Aluminum Oxide, Aluminum nitride (AlN), beryllia or beryllium oxide (BeO), silicon carbide (SiC), and boron nitride (BN), the values range from 20 to 300 W/(m·K), which is way beyond that of FR-4 printed circuit boards and more than 20 times higher.

2, Long Term Reliability: Most commercially packaged semiconductors will have a lifespan measured in years, while hybrids have a lifespan measured in decades.

3, Custom Packaging: Thick film hybrid circuits or custom monolithic IC packages provide flexibility for shape and package style, as well as the option for improved performance.

4, Small Size and Weight: In applications where a high premium is placed on small size and weight, such as aircraft and missiles, ceramic thick film hybrid circuits can offer an extremely compact, high-performance solution.

5, Low Coefficient of Thermal Expansion (CTE): Ceramic thick film hybrid circuits have solid and outstanding interatomic bonds, allowing them to withstand high temperatures and remain firm, stable, and steady even under changing temperatures.

6, Low Failure Rate: In addition to long term reliability, ceramic thick film 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, Excellent Thermal Insulation: Ceramic thick film hybrid circuits are incredibly insulating, making it less likely for heat to flow through the substrate, preserving the components of the ceramic hybrid circuit from getting damaged or harmed.

8, High Frequency: Thick film hybrid circuits can handle high-frequency applications due to their dimensional and thermal stability. Industries requiring high-frequency data and electrical signal transmissions can benefit from using Thick Film Technology.

Typical Applications of Thick Film Hybrid Circuits :

Thick Film Hybrid Circuits are widely used in various electronic applications due to their versatility and performance. These are just a few examples of the many applications of thick film hybrid circuits across different industries. Their versatility, reliability, and ability to integrate diverse electronic components make them suitable for a wide range of electronic systems and devices. Some typical applications of thick film hybrid circuits include:

1, Automotive Electronics: Thick film hybrid circuits are used in automotive electronics for Power Modules, Throttle Position Sensor, Ignition Module, Voltage Regulator, Fuel Level Sensor, and Control Modules, and other vehicle control systems.

2, Telecommunications: Thick film hybrid circuits are used in telecommunications equipment such as amplifiers, filters, and transceivers due to their ability to integrate multiple components into a single package.

3, Medical Devices: Thick film hybrid circuits are employed in medical devices such as patient monitoring systems, diagnostic equipment, and implantable devices due to their reliability and miniaturization capabilities.

4, Consumer Electronics: Thick film hybrid circuits are employed in consumer electronics products such as LED displays, audio amplifiers, and control modules due to their cost-effectiveness and compact design.

5, Aerospace and Defense: Thick film hybrid circuits are utilized in avionics, radar systems, missile guidance systems, and other defense electronics due to their ruggedness and high reliability.

6, Power Electronics: Thick film hybrid circuits are used in power management applications including voltage regulators, power converters, and motor control systems.

7, Industrial Control Systems: They find applications in industrial control systems for process control, automation, and sensing functions.

8, Sensor Interfaces: Thick film hybrid circuits are used in sensor interface applications for signal conditioning and processing in various sensor-based systems.

9, Heating Elements: Thick film hybrid circuits are used as heating elements in various applications such as industrial ovens, household appliances, automotive seat heaters, and medical devices. The thick film technology allows for the printing of resistive heating materials onto a substrate, enabling efficient heat generation and distribution.

Thick Film Hybrid Circuits offer advantages in heating applications, including precise temperature control, rapid heating response, uniform heat distribution, and the ability to integrate temperature sensors and control circuitry into the same package. These features make them suitable for a wide range of heating applications across different industries.

Manufacturing Processes of Thick Film Hybrid Circuits :

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

2, Screen-Printing Process:
All of the electrical traces (conductive, resistive, dielectric) are formed by a screen-printing process onto the ceramic substrate. The screens themselves are produced using a photomasking technique or laser cutting process known as "printed stencil". The coated regions are selectively hardened by exposure to UV light, and after the etching process, "holes" are left where the screen printing machine squeegee pushes the paste through and onto the ceramic.

3, Drying and Baking Process:
Thick film hybrid circuits that have been screen-printed onto ceramic substrates are pre-dried in an oven at 200°C before being baked at around 850°C. Additional layers, such as the conductive layer, resistive layer, and dielectric layer, are added through multiple passes of the screen-printing, drying, and baking processes. When fired, other functional elements, like dielectrics, consist of a mixture of glass and specific ceramics. These materials melt and dissolve into each other, forming a new material with specific characteristics during the firing process.

4, Multilayer Hybrid Circuit Structure:
The additive screen-printing process can be repeated multiple times using dielectric material as a protective layer to insulate the conductors. Additional metal and dielectric layers can be added, resulting in a multilayer structure. Small openings known as vias in the dielectric layers are filled with metal, connecting various circuit lines to corresponding circuit lines above or below the layer.

5, Laser Trimming Process:
One special feature of thick film hybrid circuit manufacturing is the ability to screen-print resistors along with other electrical traces. However, resistors produced through the normal process may have a tolerance of about +/-20%. In such cases, 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 area through which current flows, thereby increasing the resistance.

6, Through-Hole Metallization Process:
Thick film hybrid circuits can utilize various metals to coat and plug holes drilled through the ceramic substrate. When incorporating metallized through-holes in a design, the opposite side of the board can either act as a separate or connected circuit. Through-hole metallization with connections can be used to integrate various other conductor layers, which is a significant advantage when there is a high requirement for circuit density.

7, Inspection Process:
Any defects in the conductive or resistive traces can have an impact on the performance and lifespan of the final product. To ensure defect-free hybrid circuits during production, each thick film hybrid circuit undergoes a thorough inspection under high magnification. This inspection aims to identify defects such as opens, shorts, voids, and other potential issues before shipping the circuits.

Design Considerations of Thick Film Hybrid Circuits :

Design guideline for Thick Film Hybrid Circuits encompasses a comprehensive framework that ensures the effective integration of various components onto a single substrate, achieving high reliability and performance in electronic devices. Thick film technology involves the application of conductive, resistive, and dielectric pastes onto a ceramic substrate through screen printing techniques, followed by firing at high temperatures to achieve the desired electrical properties and mechanical strength. This technology is widely used in the manufacturing of hybrid integrated circuits (HICs), sensors, and various electronic components due to its versatility, durability, and compatibility with a wide range of materials.

● Substrate Material: Alumina (Al2O3) is the most common substrate due to its good thermal conductivity, excellent electrical insulation, and mechanical strength. Other materials like aluminum nitride (AlN) or beryllium oxide (BeO) can be used for higher thermal conductivity requirements.

● Conductive Pastes: Silver (Ag) is commonly used for conductor paths due to its high conductivity. For applications requiring lower costs or specific properties, silver-palladium (Ag-Pd), gold (Au), or copper (Cu) based pastes can be considered.

● Resistive Pastes: The choice of resistive paste depends on the required resistance value, tolerance, and temperature coefficient of resistance (TCR). Compositions vary widely, including ruthenium oxide (RuO2) based pastes for a broad range of resistance values.

● Dielectric Pastes: These are used for layer insulation and crossovers. The selection depends on the required dielectric constant, breakdown voltage, and thermal properties.

● Circuit Layout: Efficient layout design is crucial for minimizing signal interference, reducing parasitic effects, and optimizing the use of space. Considerations include trace width and spacing, pad sizes for component attachment, and the integration of passive components directly onto the substrate.

● Thermal Management: Proper thermal design ensures reliable operation and longevity. This includes the use of thermal vias, heat sinks, and the strategic placement of components to distribute heat evenly across the substrate.

● Electrical Performance: Impedance matching, signal integrity, and minimizing electromagnetic interference (EMI) are critical. The layout should consider the routing of high-speed signals, shielding, and grounding strategies.

● Screen Printing: The quality of the printed layers depends on the screen mesh size, squeegee pressure, and paste viscosity. Optimizing these parameters is essential for achieving the desired thickness and resolution of printed features.

● Firing Process: The firing profile, including ramp-up rate, peak temperature, and duration at peak temperature, affects the electrical properties and adhesion of the printed layers. Each material system has its specific firing requirements.

● Electrical Testing: Resistance, capacitance, and inductance of printed components should be measured to ensure they meet the specified values. Functional testing of the complete circuit verifies its performance against design specifications.

● Mechanical and Environmental Testing: This includes testing for adhesion strength, thermal shock resistance, and moisture resistance to ensure the circuit's reliability under varying conditions.

● Failure Analysis: Regular analysis of failure modes helps in refining the design and manufacturing process to enhance the reliability and lifespan of the thick film hybrid circuit.

● Life Testing: Accelerated life testing, under conditions exceeding normal operational stresses, provides insight into the long-term stability and reliability of the circuit.

Designing a Thick Film Hybrid Circuits require a meticulous approach to material selection, circuit layout, processing parameters, and testing. Adhering to these guidelines ensures the development of reliable, high-performance Thick Film Hybrids suitable for a wide range of applications in the electronics industry.

Laser Trimming of Thick Film Hybrid Circuits :

Laser trimming is a process used in the production of Thick Film Hybrid Circuits to precisely adjust the resistance values of resistors. In the manufacturing process, resistors are screen-printed onto the ceramic substrate along with other electrical traces. However, these resistors may have a tolerance of around +/-20% using the normal production method.

To achieve more accurate resistance values, laser trimming is employed. Each resistor is probed and measured for its actual resistance. If the measured resistance is below the target or nominal value, a laser selectively removes some of the resistive material. By doing so, the area through which current flows is reduced, effectively increasing the resistance value. This allows for tighter control over the resistance values of the resistors, typically achieving tolerances better than +/-1%.

Laser trimming helps improve the precision and performance of thick film hybrid circuits by ensuring that the resistors meet the required specifications.

Typical Stack-Up of Thick Film Hybrid Circuits :

The specific arrangement and number of layers in a Thick Film Hybrid Circuit can vary based on the desired functionality, complexity, and application requirements of the circuit. A typical stack-up of thick film hybrid circuits includes the following layers:

1, Ceramic Substrate: The base layer, made of materials such as alumina (Al2O3), beryllium oxide (BeO), or aluminum nitride (AlN). The substrate provides structural support and serves as a foundation for the circuitry.

2, Conductor Layer: The next layer is the conductor layer, which consists of metallic traces printed onto the ceramic substrate. These metallic traces can be made of materials like silver-palladium, gold-palladium, or other conductive metals.

3, Dielectric Layer: Above the conductor layer, a dielectric layer is applied. This layer provides insulation and serves as a barrier between different circuit elements, preventing short circuits and interference.

4, Resistor Layer: If resistors are incorporated into the circuit design, a resistor layer is added. This layer contains screen-printed resistors that provide specific resistance values in the circuit.

5, Additional Layers: Depending on the circuit design and requirements, additional layers can be added. These may include capacitors, inductors, or other passive components, which are integrated into the stack-up to fulfill specific functions.

6, Protective Coating: To safeguard the circuitry from external factors like moisture, temperature, and physical damage, a protective coating or solder mask may be applied on top. This layer acts as a barrier and ensures the longevity and reliability of the thick film hybrid circuits.

Why Choose PANDA PCB For Thick Film Hybrid Circuits ?

At PANDA PCB Group - Thick Film Hybrid Circuits, we specialize in providing Thick Film Solutions that offer exceptional circuit density, high performance, reliability, and cost-effectiveness. With over 20 years of experience, we have established ourselves as experts in the design and manufacture of Thick Film Hybrid Circuits for various industries such as aerospace & defense, automotive, industrial, consumer electronics, healthcare, power generation, and military applications. Here are the top reasons why you should choose Panda PCB:

1, Expertise and Experience: We have been in the industry for over a decade, accumulating extensive knowledge and expertise in manufacturing thick film hybrid circuits. Our team of skilled engineers and technicians ensures the highest quality products and efficient production processes.

2, Customization Options: We understand that every project is unique, and we offer a wide range of customization options to meet your specific requirements. Whether it's different sizes, shapes, or specifications, our team can tailor the thick film hybrid circuits to your exact needs.

3, Quality Assurance: At Panda PCB, quality is our top priority. We adhere to strict quality control measures throughout the manufacturing process to guarantee the reliability and durability of our products. Each thick film hybrid circuit undergoes rigorous testing and inspection before it reaches your hands.

4, Excellent Customer Support: Our dedicated customer support team is always available to assist you throughout the entire process. From initial inquiries to after-sales support, we are committed to providing excellent service and addressing any concerns or inquiries promptly.

5, State-of-the-Art Facilities: Panda PCB boasts state-of-the-art facilities equipped with advanced machinery and equipment. From design to production, we employ the latest technology to ensure precision, reliability, and excellent performance in our thick film hybrid circuits.

6, Timely Delivery: We understand the importance of meeting deadlines. With our efficient production processes and streamlined logistics, we ensure prompt delivery of your orders. You can rely on us to fulfill your requirements within the agreed-upon timeframe.

7, Competitive Pricing: We believe that premium quality shouldn't come at an exorbitant price. Panda PCB offers competitive pricing without compromising on the quality of our thick film hybrid circuits. We strive to provide cost-effective solutions that meet your budgetary constraints.

Make the smart choice for your Thick Film Hybrid Circuits. Choose Panda PCB and experience the reliability, quality, and efficiency that sets us apart from the competition. Contact us today to discuss your project and discover how we can fulfill your needs.

Design Guidelines of Thick Film Hybrid Circuits :

We compiled a Thick Film Hybrid Circuits-Design Guidelines as attached for you to download, It is to better support our customers' needs in designing and applying Thick Film Hybrid Circuits, 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 Hybrid Circuits to ensure adherence to best practices.

Capabilities of Thick Film Hybrid Circuits Are As Follows :

Metalization Types :

Thick Film Substrates (Screen-Printed)

Thin Film Substrates (Photo-Imaged)

Process Types :

TFM Capabilities

HTCC / LTCC Capabilities

DBC Capabilities

DPC Capabilities

AMB Capabilities

Layer Counts :

1, 2, 3, 4, 5, 6 Layers

1, 2, 4, 6, 8, 10, 12 Layers

1, 2 Layers

1, 2 Layers

1, 2 Layers

Max Board Dimension :

200*230mm

200*200mm

138*178mm

138*190mm

114*114mm

Min Board Thickness :

0.25mm

0.25mm

0.30mm~0.40mm

0.25mm

0.25mm

Max Board Thickness :

2.2mm

2.0mm

1L: 1.6mm; 2L 2.0mm

2.0mm

1.8mm

Conductor Thickness :

10um - 20um

5um - 1500um

1oz - 9oz

1um - 1000um

1oz- 22oz

Min Line Width/Space :

8/8mil (0.20/0.20mm)

6/6mil (0.15/0.15mm)

10/10mil (0.25/0.25mm)

6/6mil (0.15/0.15mm)

12/12mil (0.30/0.30mm)

Substrates Types :

AI203, ALN, BeO, ZrO2

AI203, ALN, BeO, ZrO2

Al2O3, AlN, ZrO2, PbO, SiO2, ZTA, Si3N4, SiC, Sapphire, Polycrystalline Silicon, Piezoelectric Ceramics

Al2O3, AlN, ZrO2, PbO, SiO2, ZTA, Si3N4, SiC, Sapphire, Polycrystalline Silicon, Piezoelectric Ceramics

AI203, ALN, BeO, ZrO2, Si3N4

Min Hole Diameter :

4mil (0.15mm)

4mil (0.15mm)

4mil (0.1mm)

4mil (0.1mm)

4mil (0.1mm)

Outline Tolerance :

Laser: +/-0.05mm;

Die Punch: +/-0.10mm

Laser: +/-0.05mm;

Die Punch: +/-0.10mm

Laser: +/-0.05mm;

Die Punch: +/-0.10mm

Laser: +/-0.05mm;

Die Punch: +/-0.10mm

Laser: +/-0.05mm;

Die Punch: +/-0.10mm

Substrate Thickness :

0.25, 0.38, 0.50, 0.635, 0.80,1.0, 1.25, 1.5, 2.0mm, Customizable

0.25, 0.38, 0.50, 0.635, 0.80,1.0, 1.25, 1.5, 2.0mm, Customizable

0.25, 0.38, 0.50, 0.635, 0.80,1.0, 1.25, 1.5, 2.0mm, Customizable

0.25, 0.38, 0.50, 0.635, 0.80,1.0, 1.25, 1.5, 2.0mm, Customizable

0.25, 0.38, 0.50, 0.635, 0.80,1.0, 1.25, 1.5, 2.0mm, Customizable

Thickness Tolerance :

0.25-0.38: +/-0.03mm;

0.50-2.00: +/-0.05mm

0.25-0.38: +/-0.03mm;

0.50-2.00: +/-0.05mm

0.25-0.38: +/-0.03mm;

0.50-2.00: +/-0.05mm

0.25-0.38: +/-0.03mm;

0.50-2.00: +/-0.05mm

0.25-0.38: +/-0.03mm;

0.50-2.00: +/-0.05mm

Surface Treatment :

Ag, Au, AgPd, AuPd

Ag, Au, AgPd, AuPd, Mn/Ni

OSP/Ni Plating, ENIG

OSP/ENIG/ENEPIG

OSP/ENIG/ENEPIG

Min Solder PAD Dia :

10mil (0.25mm)

10mil (0.25mm)

8mil (0.20mm)

6mil (0.15mm)

8mil (0.20mm)

Items :

Typical Values

Advanced Capabilities

1, Substrates :

FR4, Ceramic ( AI203, ALN, BeO, ZrO2), Polyimide (Flexible PI), Stainless Steel (SUS304), Mica

FR4, Ceramic ( AI203, ALN, BeO, ZrO2), Polyimide (Flexible PI), Stainless Steel (SUS304), Mica

2, Conductor (Paste) Materials :

Copper, Silver , Gold , Silver-Palladium, Palladium-Gold, Platinum-Silver, Platinum-Gold

Copper, Silver , Gold , Silver-Palladium, Palladium-Gold, Platinum-Silver, Platinum-Gold

3, Thick Film Carbon Thickness (Height) :

15um +/-5 um

30um +/-5 um

4, Conductor Thickness (Height) :

12um+/-5um

20um+/-5um

5, Min Width of Thick Film Line :

0.30 mm +/-0.05 mm

0.20 mm +/-0.05 mm

6, Min Space of Thick Film Line :

0.30 mm +/-0.05 mm

0.20 mm +/-0.05 mm

7, Min Overlap (Carbon to Conductor) :

No less than 0.25mm

0.20mm (Minimum)

8, Sheet Resistivity (ohms/square):

Printed resistors in milli ohm to mega ohm range (Customizable) with tolerances of 1-10% are fabricated and protected with overglaze materials.

Printed resistors in milli ohm to mega ohm range (Customizable) with tolerances of 0.5-10% are fabricated and protected with overglaze materials.

9, Resistor Value Tolerance (ohms) :

+/-10.0% (Standard) (Customizable)

+/-0.5% (Laser trimming)

10, Linearity :

+/-1.0% (Standard) (Customizable)

+/-0.2 ~ +/-0.5% (Laser trimming)

11, Synchronism of Double Channels :

+/-2.0% (Standard) (Customizable) (Potentiometers)

+/-1.0% (Laser trimming) (Potentiometers)

12, Durability of Carbon Ink (Life time) :

0.5 Million (Min), 2.0 Million (Standard)

5.0-10.0 Million (Max) with Surface Polishing

13, Working Temperature :

－ 40ºC /＋150ºC

－ 40ºC /＋180ºC