Skip to main content

LTCC Packaging Technology

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • Low Temperature Co-Fired Ceramics (LTCC) technology enables the creation of compact, high-performance PCB assemblies, meeting the demand for higher component densities without compromising functionality.

  • LTCC packages offer advantages such as excellent thermal conductivity, high-conductivity metallization, low dielectric loss, efficient manufacturing, mechanical resilience, and customization options for embedded components.

  • Contrasted with High Temperature Co-Fired Ceramic (HTCC) packages, LTCC packages are fired at lower temperatures, allowing for improvements in the electrical properties of the substrate. 

Circuit board layers overlaid on one another

PCBs are made out of several layers, LTCC technology allows a new way to stack these layers

With the growing need in PCB assemblies for higher component densities, methods have been developed to create compact boards without compromising performance. For this reason, Low Temperature Co-Fired Ceramics (LTCC) packaging technology has come to the forefront of packaging solutions for modern electronics. LTCC packaging technology is a manufacturing method for multilayer PCBs with low-temperature sintered ceramic materials. Each layer in these ceramic packages can have dielectric material, embedded components, low impedance conductors, and via holes to interconnect each layer. 

Applications for LTCC packages include communications/RF equipment, aerospace and military electronics, Micro Electro-Mechanical Systems (MEMS), and automotive electronics. LTCC technology is used across these different applications due to its very desirable mechanical and electrical properties, but they come at a more elevated cost and limited availability. 

Manufacturing Technology Process of LTCC Packaging 

The manufacturing process for co-fired ceramic packages is common to both the high temperature (HTCC) and low temperature (LTCC) variations. 

Step

Description

1

A mixture of ingredients (ceramics, organic resin, and a solvent) are mixed together to create a slurry. 

2

The mixture of ingredients is formed into a thin sheet via tape casting, a process where the slurry is extruded with a resin binder on a moving belt. 

3

The ceramic sheet is cut out of the mold for each layer, and vias are lasered into the ceramic according to the wiring pattern of the layer.

4

The vias are filled with a conductor material and precision conductive paste is printed on each layer.

5

The embedded components (resistors, capacitors, filters, antennas)  are placed between each layer. 

6

All of the layers in the package are laminated before sintering, or firing, all the layers at once. 

7

Solder mask and silkscreen are applied onto the outer layers of the circuit board, and all other components are mounted on the board.

Low Temperature Co-Fired Ceramic (LTCC) Packaging Technology Features

Diagram of Stackup that has LTCC Packaging Technology

Diagram of Stackup that has LTCC Packaging Technology

LTCC packaging technology has a variety of appealing features making it used in PCBs.

Feature

Description

Thermal Conductivity

The ceramic substrate used in LTCC technology has excellent thermal conductivity properties, useful for dissipating power from components on a circuit board in the form of heat.

High-Conductivity Metallization

Metallization, the process of coating or injecting a material of metallic compound on a circuit board, uses metals with lower melting points and higher conductivity, like silver and gold, to improve electrical properties and speed of transmission for data in lower temperature processes.

Dielectric Loss

LTCC offers better dielectric loss than alternatives, important for high-speed, high-volume data transmission, benefiting technologies like 5G and IoT, due to the ceramic’s chemical properties.

Efficient Manufacturing

LTCC packaging features a single laminification and sintering process for all substrate layers, making it more efficient than traditional bulk substrate manufacturing that requires sequential steps.

Mechanical Properties

The lamination and sintering process creates a strong hermetic seal in the ceramic, providing mechanical resilience desirable for aerospace and military uses.

Customization

Allows embedding components such as resistors, capacitors, inductors, and balun antennas between layers, freeing up space on the PCB's outermost layers for other components. This added compactness is key for the fabrication of Multi Chip Modules (MCMs) and Systems on a Chip (SoC) on LTCC packaging.

Disadvantages of LTCC Packaging

  • Thermal Conductivity: Compared to High Temperature Co-Fired Ceramic (HTCC) packages, low temperature sintered ceramics have worse thermal performance. This is the reason why HTCC ceramics are the most preferable substrates for use in high temperature environments like industrial electronics. 

  • Cost: The ceramic material comes at a higher cost than the bulk substrate used in PCBs. The price is even more elevated if costly metalization processes are used to enhance conductivity of the vias. 

  • Availability: Long lead times are a problem for LTCC devices, since the manufacturing process is not widely used, but new investment in semiconductor manufacturing will likely increase the supply of these kinds of packages.

Differences between LTCC and HTCC Packaging Technology

The process for manufacturing LTCC and HTCC packages is similar, but the difference is the temperature at which they are sintered, which changes the properties of each package. 

  • LTCC packages are fired at 800℃ to 900℃. This temperature range makes it possible that lower melting point and higher conductivity metals like gold and silver are used for the traces in vias of the PCB. This higher speed of electric transmission is key for fast digital circuits and RF applications. 

  • HTCC packages are fired at temperatures higher than 1000℃, which require metals with higher melting points to be used, like tungsten and molybdenum that offer worse electrical properties than in LTCC metalization. Rather, the advantage of using HTCC is in its excellent thermal conductivity characteristics. 

Cadence Offers Tools for LTCC Packaging Technology

Low Temperature Co-fired Ceramic (LTCC) packaging technology is used in a wide variety of industries, and has proven to have a repeatable, simple manufacturing process that produces robust substrates to make excellent circuit boards. An essential part of the package development process is to be equipped with the best tools for the job. Design tools like Allegro X Advanced Package Designer offer features to design, characterize, validate, and enhance multi-layer ceramic packages with ease and confidence. 

Leading electronics providers rely on Cadence products to optimize power, space, and energy needs for a wide variety of market applications. To learn more about our innovative solutions, talk to our team of experts or subscribe to our YouTube channel.