HTCC and LTCC, can you tell the difference?

With the rise and application of power devices, especially the third generation semiconductor devices, semiconductor devices are gradually developing in the direction of high power, miniaturization, integration and multi-function, which also puts forward higher requirements on the performance of packaging substrates. Ceramic substrates are widely used in the packaging of electronic devices because of their high thermal conductivity, good heat resistance, low coefficient of thermal expansion, high mechanical strength, good insulation, corrosion resistance, and radiation resistance.
Co-fired multilayer ceramic substrates can simultaneously produce electrode materials, substrates, and electronic devices to achieve high integration, and are widely used in high-power device packaging.
Co-fired multilayer ceramic substrates are made from multiple single ceramic substrates by lamination, hot pressing, debinding, and sintering processes. Since more layers can be manufactured, the wiring density is higher, the interconnection length can be minimized, and the assembly density and signal transmission speed can be increased. Therefore, it can adapt to the requirements of electronic machinery for circuit miniaturization, high density, multi-function, high reliability, high reliability, high speed, and high power.
According to the difference of temperature in the preparation process, the co-fired ceramic substrate can be divided into high-temperature co-fired ceramic (HTCC) multilayer substrate and low-temperature co-fired ceramic (LTCC) multilayer substrate.
So what is the difference between these two technologies?
In fact, the production process of both is basically the same, both need to go through the preparation process of paste preparation, cast, blank drying, drilling, screen printing filling holes, screen printing circuits, lamination sintering, and finally slicing. While HTCC technology is a co-sintering technology with a sintering temperature higher than 1000°C °C. Sintering is usually performed at 900 °C 1650 to 1850 °C. Compared to HTCC, the sintering temperature of LTCC is lower, generally below 950°C °C. High temperature ceramics have the disadvantages of high sintering temperature, high energy consumption, and limited metal conductor material, driving the development of low temperature ceramic processes.
The difference in sintering temperature affects first the choice of material and then the performance of the product, resulting in two products suitable for different application directions.
HTCC substrates are not suitable for high-speed or high-frequency microassembly circuit substrates because of the high sintering temperature, which prevents the use of low-melting-point metal materials such as gold, silver, and copper, and necessitates the use of refractory metal materials such as tungsten, molybdenum, and manganese, which have high manufacturing costs and low conductivity and can cause defects such as signal delays. However, due to the high sintering temperature of the material, it has high mechanical strength, thermal conductivity and chemical stability. It also has the advantages of wide material sources, low cost, and high wiring density. HTCC substrates have greater advantages in the field of high-power packaging, which places higher demands on their thermal stability, mechanical strength, thermal conductivity, hermeticity, and reliability.
LTCC substrates reduce the sintering temperature by adding amorphous glass, crystalline glass, and low melting point oxides to the ceramic paste. Metals with high conductivity and low melting point such as gold, silver and copper can be used as conductor materials, which not only can reduce the cost but also can obtain good performance. Microcrystalline glass has the advantages of low dielectric constant and low loss at high frequencies, making it ideal for RF, microwave and millimeter wave devices. However, due to the addition of glass material to the ceramic paste, the substrate has low thermal conductivity and low sintering temperature, so the mechanical strength of the substrate is not as good as that of HTCC substrate.
Therefore, the difference between HTCC and LTCC remains a case of performance variation, each with its own advantages and disadvantages. The appropriate product must be selected according to the specific application conditions.
Differences between LTCC and HTCC
In conclusion, HTCC substrates with their proven process and inexpensive dielectric materials will play an important role in electronic packaging in the long term. However, with the continuous improvement of materials, process control and technology maturity, the natural advantages of LTCC will become more prominent and more adaptable to the development trend of high frequency, high speed and high power. However, various substrate materials have their own advantages and disadvantages. Due to the different requirements of the specific application circuit, the performance requirements of the substrate materials are also different. Therefore, a variety of substrate materials will co-exist and develop in the long term.