Manufacturing Process
.A comprehensive overview of ceramic substrate manufacturing technologies, from material preparation and metallization to advanced bonding processes for reliable electronic systems.
what is manufacturing process?
The manufacturing process of ceramic PCB is an important stage in production. It is directly influence product quality and the product cost. The features like surface flat, surface roughness and dimensional stability pave the way for metallic deposits and circuit patterning processes. In high temperature, the wetting ability between metal and ceramic surface decides their bonding strength. Bonding strength is fundamental of properties. Thus, metal processing focus on depositing conductive layer of metal onto ceramic surfaces and ensuring reliable bonding at the metal ceramic interface. Which pose high demands for manufacturing.
Manufacturing Process Overview
DBC
Direct bond copper is a way to bond metal to metal directly. If copper is the bonding materials. It called Direct Bond Copper. DBC substrate are produced through a sequence of processes that include copper foil oxidation, ceramic to copper bonding under high temperature conditions, circuit board pattern formation, etching, cleaning, and final surface finishing. Inside metal and ceramic form a transition layer while the bonding process. It created by the two materials via oxygen mediated interfacial connections. There is no obvious reaction layer or intermediate phase is generated between them. DBC technology can realize hundreds micrometers thickness of copper layer. It is appropriate for power electronics to heat transfer and current outlet.
AMB
Active Metal Brazing substrate is consist of copper and ceramics together by active brazing at above 450 °C. In brazing, a low melting filler material is introduced between the base materials. The molten filler penetrates the joint through capillary action and forms a reliable bonding by adhering well to the contacting surfaces. Which provide electronic insulation between semiconductor chip and the plate. While also maintaining efficient heat dissipation. However, as different CTE of AMB materials, AMB substrate are distortion by temperature change, leading to thermal stress fatigue.
DPC
Direct Plated Copper is a way to form ceramic metal. DPC manufacturing includes via hole drilling, sputtered seed layer deposition, circuit pattern, copper electroplating, etching, and surface finishing, enabling the fabrication of high precision ceramic PCB for advanced electronic packaging. DPC technology adopt semi additive process to create the pattern, by plating process and photo imaging to realize high and accurate pattern. However, for thick copper, the copper plating time is prolong, which could generate fracture stress in the electroplated copper layer.
Thick Film
Thick film materials involves inorganic powders mixed with organic carrier media to form processable coating pastes. They are frequently apply in conductor formation, resistors, and circuit board. Thick film technology also can be use to produce complicated multiply circuit, achieving by alternating conductive patterns and insulating dielectric layer throughout the substrate. The low production cost and board application versatility making thick film suit for massive production. Which easy screen changeover also support rapid prototyping and short run manufacturing of diverse products. Various raw materials, including metallic compounds, oxides, solvents, and resins, undergo specialized processing to generate intermediate products such as materials conductivity, glass materials, and formulation vehicles for electronic manufacturing.
LTCC
The low temperature cofired ceramics technology applied in ceramic based meso and microsystems since electrical and mechanical properties. LTCC technology can realize high reliability in high temperature, like downhole oil and gas monitoring and aerospace sensing systems, where components must withstand elevated temperatures, high pressures, and corrosive gases. The difficults of developing LTCC are sintering behavior and chemical compatibility. In order to fabricate LTCC modules with embedded electrode structure, the ceramic material must be densified at temperatures that do not exceed the melting point of the embedded electrodes. The typical materials are Ag, Cu, Au, among them sliver is the common choice and the melting point is 961℃. Therefore, the temperature of LTCC technology must control below 900 ℃ or lower.
HTCC
HTCC are based on stacking tape cast ceramic dielectric layer, onto which conductive trace, resistors, and capacitive elements are formed through screen printing process. The high temperature cofired ceramic substrate have been used in microelectronic and packaging assembly, owing to the outstanding properties, low cost and easy to fabricate. . It also used to make complicated components, applying in elevated temperature. The HTCC process includes drilling via holes in ceramic green tapes, printing tungsten or molybdenum conductors, stacking and laminating multiple layers, then co firing at temperature above 1500°C. which produce robust multilayer ceramic structure with integrated conductive networks. The process have restriction on the complexity of the metallic network, because pattern is limited to 2D patterns. This also limit the function of electronic components.
Related Manufacturing Techniques
Metallization
Metallization need to satisfy all kinds of requirements, there is no single metal solution to meet all needs. The metallization process should be carefully selected according to the device requirements, including contact characteristics, operating conditions, circuit density, conductor dimensions, and packaging specification. Screen printing is changing the technology of the world via low cost and portable devices. It is available to massive production of batteries, sensors, and electronic devices. Which reduce the cost and bring more benefits for consumer product design like flexible solar panels, RFID enabled products, smart home devices, wearable electronics. Gold plating can be divided into hard gold and soft gold. Soft gold coatings provide an ideal surface for wire bonding, facilitating the attachment of gold or aluminum wire to semiconductor devices mounted on circuit boards. Hard gold provide excellent resistance to mechanical wear and oxidation. It is suit for electrical connector and contact interfaces that demand long term reliability and low resistance. Meanwhile, the Electroplated gold has become a preferred surface finish in electronic application.
Circuit formation
Circuit board design are closely linked to design variables, which influence the overall electrical response and functionality of the system. Etching is a part of IC board design. To meet the strict requirements of fabrication, etching technology has evolved alongside sophisticated diagnostic techniques, surface analysis methods, and improved equipment design.
Joining Processes
In engineering application, it is necessary for any materials to jointing. However, welding or bonding two materials of joint process always cause deterioration of the microstructural and mechanical properties of materials. Thus, the jointing process and material compatible need to be attention.
Common joining techniques include soldering, brazing, and welding. Among these methods, solder joint reliability depends largely on the wettability between the solder alloy and the base materials, as well as the effectiveness of the flux and the characteristics of the joining materials. Welding is a fabrication process that joins two contacting materials by melting and fusing their interface, the melting is below 450°C to prevent metal melting. The choice of joining technology is determined by factors such as operating conditions, mechanical strength requirements, electrical performance, and thermal management considerations. Therefore, proper process selection is essential to ensure the reliability and durability of the final assembly.
Manufacturing Challenges
The manufacturing of ceramic substrates involves several technical challenges that can affect performance and reliability. Thermal stress can develop during heating and cooling cycles due to differences in the coefficient of thermal expansion (CTE) between ceramic materials and metal layers. Delamination may occur when bonding strength is insufficient, leading to separation between the ceramic and metallization layers. Adhesion for copper is another critical factor, as poor bonding can reduce integrity mechanical and electrical reliability. In addition, precise metal patterning and cutting processes are essential for achieving accurate circuit geometries and preventing defects in conductive layers. Maintaining longterm reliability under high temperatures, power cycling, and harsh operating environments remains a key consideration for advanced ceramic substrate applications.
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