Introduction

LTCC (Low Temperature co-fired Ceramic) is an integrated component technology developed since 1982. It has become the mainstream technology of passive integration, the development direction of passive components and the economic growth point of the new component industry.

LTCC technology is a new kind of material in 1982 hughes company development technology, is the low temperature sintering thickness precision ceramic powder and the density of porcelain, born in the porcelain with use, micro hole grouting, precision laser drilling conductor size printing technology to produce need circuit graphics, and will be more passive components, such as low capacitance value capacitor, resistor, filter, impedance converter, coupler, etc.) sat on a multilayer ceramic substrate, and then the overlying together, the internal and external electrode respectively using silver, copper, gold and other metals, sintered under 900 ℃, made from three dimensional space of high density circuit each other noninterference,It can also be made into a three-dimensional electric subgrade board with built-in passive components. IC and active components can be mounted on its surface to make passive/active integrated functional modules, which can further miniaturize and densify the circuit, especially suitable for high-frequency communication components.

So, various high-tech LTCC products can be successfully manufactured by using this technique. Several passive components of different types and performance can be integrated into one package in various ways, including low temperature co-fired ceramics (LTCC) technology, thin film technology, silicon wafer semiconductor technology, multi-layer circuit board technology, etc. LTCC technology is the mainstream technology of passive integration. LTCC integrated components include products with va rious substrates bearing or embedding various active or passive components, while integrated component product projects consist of components, substrates, and modules.

Technical advantages

1. Comparative advantages

Compared with other integration technologies, LTCC has many advantages:

1, ceramic materials have excellent high frequency, high speed transmission and wide pass band characteristics.According to different ingredients, the dielectric constant of LTCC material can vary in a wide range. In combination with the use of metal material with high conductivity as the conductor material, it is beneficial to improve the quality factor of the circuit system and increase the flexibility of circuit design.

2, it can adapt to the requirements of high current and high temperature resistance, and has better thermal conductivity than ordinary PCB subgrade board, greatly optimizing the heat dissipation design of electronic equipment, high reliability, can be applied in harsh environment, extend its service life;

3, the electric subgrade board with a high number of layers can be made and multiple passive components can be embedded in it, which eliminates the cost of packaging components. In the three-dimensional electric subgrade board with a high number of layers, the integration of passive and active components can be realized, which is conducive to improving the assembly density of the circuit and further reducing the volume and weight.

4, it is compatible with other multilayer cabling technologies, such as LTCC combined with thin-film cabling technology to achieve higher assembly density and better performance of hybrid multilayer substrates and hybrid multichip components;

5, the discontinuous production technology facilitates the quality inspection of each layer wiring and interconnect through hole before the finished product is made, which is beneficial to improve the yield and quality of multilayer substrate, shorten the production cycle and reduce the cost.

6, energy saving, material saving, green and environmental protection have become the irresistible trend of the development of the component industry. LTCC also caters to this development demand and reduces the environmental pollution caused by raw materials, wastes and the production process to the greatest extent.

2. Application advantages

(1) More wiring layers can be easily realized to improve assembly density;

(2) Easy to embed components, improve assembly density, and achieve multi-function;

(3) Facilitate the quality inspection of wiring of each layer and interconnection through holes before the substrate is burned, which is conducive to improving the yield and quality of multi-layer substrate, shortening the production cycle and reducing the cost;

(4) It has good high-frequency and high-speed transmission characteristics;

(5) It is easy to form cavities with various structures, so as to realize multi-functional microwave MCM with excellent performance;

(6) Good compatibility with thin film multi-layer wiring technology, the combination of the two can achieve higher assembly density and better performance of hybrid multi-layer substrate and hybrid multi-chip components (McM-c /D);

(7) Easy to realize multi-layer wiring and packaging integration structure, further reduce the volume and weight, improve the reliability.

Due to its unique advantages, LTCC technology will show great advantages when used to produce surface assembled components in the new generation of mobile communications.

3. Technical characteristics

LTCC has many advantages in preparing chip passive integrated devices and modules. Firstly, ceramic materials have excellent high frequency and high characteristics. Secondly, using metal material with high conductivity as conductor material is beneficial to improve the quality factor of circuit system.Thirdly, it can meet the requirement of high current and high temperature resistance, and has better thermal conductivity than ordinary PCB subgrade board.Fourth, the passive components can be embedded into the multi-layer subgrade plate, which is beneficial to improve the assembly density of the circuit.Fifth, with better temperature characteristics, such as smaller thermal expansion coefficient, smaller permittivity temperature coefficient, can be made of very high layers of electric subgrade board, can be made of line width less than 50 m thin line structure.In addition, the discontinuous production process allows the inspection of the raw substrate, thus improving the yield and reducing the production cost.

One of the significant advantages of LTCC devices is their good consistency and high accuracy.This depends entirely on the stability of the materials used and the accuracy of the processing equipment.There is no manufacturer in China that can manufacture LTCC related molding equipment.According to incomplete statistics, Domestic South Glass Electronics has introduced a complete LTCC production line, and about 4 research institutes have or are introducing LTCC pilot test equipment to develop LTCC modules for military use.

Prospects

In addition to its applications in mobile phones, LTCC has become the preferred way to integrate and modular electronic components in the future due to its excellent electronic, mechanical and thermal properties. LTCC can be widely used in military, aerospace, automotive, computer and medical fields.

1. The trend

LTCC is a trend of component manufacturing process in the future, and the trend of integration is very obvious.According to industry experts, COMPARED with other integration technologies, LTCC has the following characteristics: The dielectric constant of LTCC materials can vary widely depending on the ingredients, increasing the flexibility of circuit design;Ceramic materials have excellent characteristics of high frequency, high Q and high speed transmission.Using metal material with high conductivity as conductor material is beneficial to improve the quality factor of circuit system.To fabricate the subgrade board with high number of layers to reduce the length and connection points of the conductor of the chip, and to fabricate the circuit with fine line structure with line width less than 50 m, so as to realize more wiring layers, more integrated components, wide range of parameters, easy to realize multifunction and improve the assembly density;It can meet the requirement of high current and high temperature resistance and has good temperature characteristics.It has good compatibility with thin film multi-layer wiring technology, and the combination of the two can realize hybrid multi-layer substrate and hybrid multi-chip components with higher assembly density and better performance.Easy to realize multi-layer wiring and packaging integration structure, further reduce the volume and weight, improve reliability, high temperature resistance, high humidity, can be applied in harsh environment;The discontinuous production technology facilitates the quality inspection of each layer wiring and interconnect through hole before the substrate is fired, which is beneficial to improve the yield and quality of multilayer substrate, shorten the production cycle and reduce the cost.

2. The application

LTCC products are widely used in various fields, such as mobile phones, Bluetooth modules, GPS, PDA, digital camera, WLAN, automotive electronics, optical drive, etc.Among them, mobile phone usage accounts for the main part, about more than 80%;Secondly, bluetooth module and WLAN.Applications in automotive electronics are also on the rise due to the high reliability of LTCC products.LTCC products used in mobile phones include LC filters, diplexers, function modules, transceiver switch function modules, balanced to unbalanced converters, couplers, power dividers, common mode chokers, etc.

LTCC technology in SMD is designed to increase assembly density, reduce volume, reduce weight, increase functionality, improve reliability and performance, and shorten assembly cycles.VCO is a key component of mobile communication equipment. LTCC technology can be used to produce VCO to meet the requirements of mobile communication for small size, light weight, low power consumption and low phase noise (high C/N ratio).Internationally, LTCC technology has been used to make high-performance tables and assembled VCO, and a series of commodities have been formed. The VOLUME of VCO has been greatly reduced by adopting LTCC technology.Between 1996 and 2000, the volume of VCO decreased by more than 90%.The volume of the assembled VCO is only 1/5-1/20 of the volume of the original meter-lead VCO.The new VCO made by LTCC technology has the advantages of small volume, low power consumption, good high-frequency characteristics, small phase noise, suitable for surface mount, etc., and has been widely used in the field of mobile communication.This miniaturized VCO is widely used in digital communication system terminals such as GSM, DCS, CDMA and PDC, as well as satellite communication terminals such as GLOBAL positioning system (GPS).

The rapid development of mobile communication has further promoted the miniaturization of DC/DC converters, providing a broad application market for SMD TYPE DC/DC converters.Many foreign power manufacturers are using LTCC technology to actively develop standard SMD type DC/DC converter, its rated power is 5-30W, with a variety of common input and output voltages.Some new DC/DC converter designs also offer shorter start-up times.In addition, LTCC technology is also used to make mobile credit chip multi-layer antenna, Bluetooth components, rf amplifier voltage-controlled attenuator, power amplifier, shifter and other meters and installation devices.