Posts Tagged ‘ceramic PCB’

What Are the Different Types of Ceramic PCBs?

星期六, 6 7 月, 2024

Ceramic PCBs are a special breed of printed circuit boards known for their exceptional thermal resistance and durability. These PCBs are used in industries where high performance is critical, such as aerospace, automotive, medical devices, and power electronics. Nowadays, the most common types of ceramic PCB are thick film, DCB, DPC, AMB, HTCC, LTCC and thin film. In this article, we will introduce each of them in details.

What are the different types of ceramic pcbs?

Thick Film Ceramic PCB

Thick film technology is a process by using screen printing conductor paste and directly deposit slurry (conductor) on the ceramic substrate. Then sintering it under high temperature to form conductive circuit traces and electrodes, which is suitable for most ceramic substrates.

After the material is sintered at high temperature, a strong adhesion film will be formed on the ceramic circuit board, repeat this step for many times, a multi-layer circuit is generated.

You can print resistor or capacitor on the surface to get a interconnected structure. At Best Technology, we can make all the resistors with the same value, or different value for different resistor on the same board.

Thick film ceramic PCB has advantages on the simple manufacturing process, but it has some drawbacks that can’t be ignored:

Limited by the conductive paste and screen size
Line width less than 100um is difficult to achieved
Three-dimensional patterns are not available
Not suitable for fine-trace project

DBC / DCB Ceramic PCB

Direct Bonded Copper (DBC) or Direct Copper Bonded (DCB) ceramic PCBs are known for their excellent thermal conductivity. They are made by bonding a layer of copper directly onto a ceramic substrate, typically aluminum oxide or aluminum nitride. Due to the DBC technology is directly bond copper on the ceramic substrate, it can achieve thicker copper thickness to 300um. So, it is very suitable for high power applications.

The basic chemistry principle is to introduce an appropriate amount of oxygen between copper and ceramics before or during the application process. Copper and oxygen will form Cu-O eutectic liquid under 1065℃~1083℃. This is an important element in the manufacturing. DBC ceramic circuit board uses this eutectic solution to chemically react with the ceramic substrate to form CuAlO2 or CuAl2O4, achieving the combination between substrate and copper foil.

However, it is easy to generate micro-porosity between Al2O3 and Copper during the copper bonded process, and it doesn’t have a good solution by far. That is why the yield of DBC ceramic PCB is not good than DPC.

DPC (Direct Plated Copper Ceramic PCB)

DPC ceramic PCB utilizes direct copper plating technology, deposit copper foil on the alumina oxide (Al2O3) substrate. It is the most commonly used ceramic PCB in recent years. The circuit generated process is: pre-treatment – sputtering – exposure – develop – etch – strip – electroplating.

AMB (Active Metal Brazed Ceramic PCB)

AMB ceramic copper clad plate adopts the active brazing process, and the copper layer bonding force is higher than that of DPC, which is around 18n/mm – 21n/mm. AMB ceramic copper clad plate usually has a high binding force, usually makes thicker copper, between 100um and 800um. The AMB ceramic PCB generally rarely design traces or holes, even if there is a trace is very simple, the spacing is relatively wide.

HTCC (High Temperature Co-fired Ceramic PCB)

HTCC is a relatively early development technology, but due to the high sintering temperature (1300~1600℃), the choice of electrode materials is limited. Meanwhile, its cost is more expensive, these promotes the development of HTCC is relatively slow.

LTCC (Low Temperature Co-fired Ceramic PCB)

Although LTCC reduces the co-firing temperature to about 850 ° C, the disadvantage is that the dimensional accuracy and product strength are not easy to control.

Thin Film Ceramic Circuit Board

The thin film ceramic PCB is to deposit a metal layer directly on the surface of substrate by sputtering process. Through lithography, development, etching and other processes, the metal layer can also be graphed into a circuit pattern. Due to the low deposition speed of sputtering coating (generally less than 1μm/h), thin film substrate surface metal layer thickness is small and can prepare high pattern accuracy (line width/line space less than 10μm).

Common Ceramic Substrates

Best Technology is a leading ceramic PCB manufacturer in Asia, our core members has over 20 years manufacturing experience in ceramic PCB fabricating. “High mixed, low volume, high quality, fast delivery” is our advantages and we always try our best to do that, make ourselves better and better. If you are interested in it, feel free to contact us, we are always online.

What is Ceramic PCB?

A ceramic PCB is a type of PCB made from ceramic materials, such as alumina (Al2O3), ALN (aluminum nitride), or Beryllium Oxide (BeO). These materials are prepared by using thermal conductive ceramic powder and organic adhesive under the condition of below 250℃. Ceramic powders are not easy to made, especially for aluminum nitride powder, this is one of reasons that why ALN ceramic PCB is more expensive.

There are some different methods to make ceramic PCBs, commonly in the market are thick film, DBC, DPC and thin film technology. Different types of ceramic circuit boards have its unique characteristics. May you heard about HTCC, LTCC and AMB, they are also the ways to make ceramic PCBs, but there just a few manufacturers can make. Here is a HTCC ceramic PCB that we made.

Why Ceramic PCBs are popular used?

Different from the traditional FR-4 PCB (wave fiber), ceramic PCBs have good high-frequency properties, electrical properties that organic materials can’t achieved. It is a new generation of large-scale integrated circuits and power electronics module ideal packaging materials. The main advantages of ceramic circuit board including:

Higher thermal conductivity
More matched thermal expansion coefficient (CTE)
Lower resistance
Good weldability and can be used in high temperature
Good insulation
Lower high-frequency loss
High density assembly available
No organic ingredients, resistance to cosmic rays, high reliability in aerospace
No oxide layer in copper layer, so it can be used for a long time in a reducing atmosphere

Who is the Best Ceramic PCB Manufacturer?

There are so many PCB manufacturers in the domestic and aboard, but reliable ceramic PCB vendors with good quality and reasonable price are very few. If you are looking for an experienced one, then keep the change. We’re the best option! Best Technology offers ceramic PCBs for our customers more than 100k every year, and we are high mixed from thick film ceramic PCB, DPC ceramic PCB, DBC/DCB ceramic PCB to AMB. Your PCBs need to use in automotives? Don’t worry, we gained IATF16949 and ISO13485 certifications, and all the manufacturing processes are strictly followed by ISO9001 quality control system. We welcome all the questions and inquiries from everyone.

Here is our ceramic PCB manufacturing capability for your reference.

Ceramic PCB Manufacturing Capability
No.	Item		General Parameter	Special Process
1	Substrate	High insulation, chemical corrosion resistance, high-temperature resistance	Al2O3	Glass, quartz, sapphire, 99% , 92% Al2O3 (black)
2		Excellent thermal conductivity, low thermal expansion coefficient, and high-temperature resistance	AIN
3		Insulation performance and high-temperature stability	ZTA
4		High strength, high hardness, high thermal conductivity, and low dielectric loss	Si3N4
5		Conductor	Tungsten（LTCC/HTCC)、Au、Au&Pd、Au&Pb、Ag、Ag&Pd、Ag&Pb
6	Layer Count	DPC	Single – Double sided
7		DBC	Single – Double sided
8		AMB	Single – Double sided
9		Thick film	Single – Double sided, 4L
10		LTCC	Single – Double sided, 4L, 6L	6L – 14L
11		HTCC	Single – Double sided, 4L, 6L
12	Copper Thickness	Inner layer	/
13	Copper Thickness	Outer layer	Hoz-3oz (DPC), 3oz-12oz(DBC/AMB)
14	Dimension	Max. dimension	130*180	Larger dimension available (pass evaluation)
15		Min. dimension	2*2	Shipped in panel
16		Substrate thickness	Al2O3/AIN 0.38. 0.635, 1.0mm, Si3N4 0.25、0.32mm	>1.5
17	Surface Treatment (thickness)	OSP	0.2-0.5um	/
18		ENIG	1-3u”（Au）120-320u”（Ni）	/
19		Immersion silver	6-12u”	/
20		Immersion tin	≥1um	/
21		ENEPIG	Au 2u”, Pd 1U”, Ni 100u”	/
22		Hard gold	5-30u”（Au）、120-200u”（Ni）	/
23	Drill	Min. PTH	0.05MM	/
24		Min. NPTH	0.05MM	/
25		Max. aspect ratio (PTH PCB)	5:1	/
26		NTPH tolerance	±0.05	/
27		PTH tolerance	±0.05	/
28	Line width/ Line spacing	Inner layer	Line width≥0.1mm; Line space≥0.1mm	0.076/0.076mm
29		Outer layer	1OZ; Line width≥0.12mm; Line space≥0.12mm	0.1/0.1mm
30			2OZ；Line width≥0.2mm; Line space≥0.2mm	0.15/0.15mm
31			3OZ；Line width≥0.25mm; Line space≥0.25mm	0.2/0.2mm
32			4OZ；Line width≥0.35mm; Line space≥0.35mm	0.3/0.3mm
33			5OZ；Line width≥0.45mm; Line space≥0.45mm	0.4/0.4mm
34			6OZ；Line width≥0.55mm; Line space≥0.55mm	0.5/0.5mm
35			Thick film; Line width≥0.1mm; Line space≥0.1mm	0.076/0.076mm
36		Line width tolerance	±20%	/
37	Solder Mask (SM) /Silkscreen	Conductor	Glass glaze, medium, solder mask ink	/
38		SM color	White, black, green	Mixed color
39		Silkscreen color	White, black	Mixed color
40		Silkscreen height, width	Line width≥0.13mm; Height≥0.8mm	/
41		SM thickness	≥20um	/

What is thick film ceramic board?

The “Thick Film” refers to the thickness of conductor layer on a Ceramic PCB. Normally the thickness will be at least 10um, around 10~13um, which is thicker than spurting technology in Thin Film Ceramic PCB. And of course thickness is less than DCB Ceramic board or FR4 board.

Thick film ceramic circuit enables to put resistor, electric capacitor, conductor, semi-conductor, and interchangeable conductor on ceramic board, after manufacturing steps of printing and high temperature sintering. The more important thing is by using thick film technology, we can make all the resistors with the same value, or different value for different resistor on the same board.

Materials and processes for via holes

In general, thick film ceramic circuit is not suitable for designing via holes. Because the characteristics of thick film ceramic board mainly depends on the insulation properties of its ceramic substrate, rather than conductive properties. The conductivity of thick film ceramic plate is not good than Metal Core PCB, or even we can say it has a very poor conductivity, usually can’t meet the requirements of the via hole.

But, designing via holes in thick film ceramics is available in Best Technology. Generally speaking, the fabrication of via holes in thick film ceramic boards typically involves several key materials and processes.

From the designer’s perspective, a conductive material is used to create a continuous conductive path from one side of the ceramic board to the other. Common conductive materials include gold paste, silver paste, and copper paste. These materials are usually screen printed onto the ceramic board in the desired pattern, and then fired at high temperatures to achieve sintering and form a conductive layer.

Once the conductive layer is formed, the via holes are created by drilling or punching small holes through the ceramic board at the desired locations. These holes are then filled with a conductive material, such as silver paste or copper paste, to establish electrical connections between the different layers of the circuit.

Finally, the via holes are fired again at high temperatures to achieve sintering and ensure good adhesion and electrical performance.

Advantages of Via Holes in Thick Film Ceramic Boards

These via holes offer several advantages in the design and fabrication of thick film ceramic boards, including as following:

Electrical connectivity

Via holes provide electrical connectivity between different layers of a thick film ceramic board. They allow for the interconnection of different circuitry or conductive layers, enabling the flow of electrical signals or power between different parts of the board. This allows for complex and multi-layered circuit designs, which can be highly beneficial in applications that require intricate circuitry or high-density interconnects.

Space-saving

Via holes can provide a means of vertical interconnection, allowing for more efficient use of board real estate. Instead of routing traces or conductors on the surface of the board, which can take up valuable space, via holes can be used to route connections through the board, freeing up surface area for other components or functions. This is especially advantageous in compact or miniaturized electronic devices where space is limited.

Thermal management

Via holes can aid in thermal management in thick film ceramics. They can be used to transfer heat from one layer of the board to another, helping to dissipate heat generated by components or circuits. This can be particularly important in high-power or high-heat applications, where efficient thermal management is crucial for preventing overheating and ensuring reliable performance.

Mechanical stability

Via holes provide additional support and reinforcement to the board, reducing the risk of warping, bending, or cracking. Via holes can also help improve the overall mechanical integrity of the board by reducing stress concentration points and enhancing its structural rigidity.

Design flexibility

Via holes offer design flexibility in thick film ceramic boards. They can be designed and placed according to the specific requirements of the circuit or system, allowing for customized and optimized designs. Via holes can be used to route traces, create vias for component mounting, or provide grounding or shielding, among other functionalities. This flexibility in design allows for more efficient and effective circuit layouts, which can lead to improved performance and reliability.

As previously mentioned, designing via holes in thick film ceramic boards offers various benefits. However, when it comes to choosing the appropriate paste for via holes, silver paste is often recommended to our customers. But why is that? Can I use gold or copper? In our upcoming article, we will delve into the reasons behind this recommendation and provide you with valuable insights. Stay tuned to uncover the answers!

Oxidation technology of copper foil

Copper oxidation is divided into Wet Air Oxidation (including soaking oxidation and spraying oxidation) and Dry Oxidation. Both oxidation methods can form CuO or Cu2O on the surface of copper foil.

Wet Air Oxidation (WAO)

i. Soaking oxidation

First, the copper is pickled with 3% dilute sulfuric acid, and then washed by the spray washing machine after overflow. Next, sent the copper into the mixed solution of potassium permanganate and copper sulfate (the concentration of potassium permanganate is about 31.6mg/L and the copper sulfate is about 95.4mg/L) for soaking and oxidation. The oxidized copper is then washed with water and three-stage countercurrent washing, and then slowly pulled for dehydration and drying (the temperature is about 100℃) to complete soaking and oxidation.

ii. Spraying oxidation

Spraying oxidation is a kind of WAO, only the oxidation method become spraying. Spray oxidation is to spray copper with mixed solution of manganese nitrate and copper nitrate (concentration of about 3%) after pickling and washing. The sprayed copper is dried directly in the tunnel kiln (the temperature is about 200℃). In the drying process of tunnel kiln, the manganese nitrate and copper nitrate sprayed on the copper sheet are decomposed into copper oxide and manganese oxide. The ratio of soaking oxidation and spraying oxidation treatment of copper sheet is about 5:5.

Dry Oxidation

Dry oxidation is very easy to process, put the copper into oxidation oven firstly, then heating up to 600~800^oC for oxidizing around 30mins and then subjected to air cooling annealing.

Wet Air Oxidation VS Dry Oxidation

At present, the existing industry is widely used to finish the high-temperature annealing oxidation of copper then sintering with ceramic substrate, that is dry oxidation. But this high temperature annealing, oxidation in one way has some drawbacks as following:

Uneven oxidation. It will directly cause sintering defects during sintering, and the peeling strength will change greatly.
Leaving conveyor belt marks. Because the high temperature and oxidation process is transported by the conveyor belt, the existence of the conveyor belt mesh will affect the temperature distribution of the entire copper is not uniform, leaving marks/traces of the conveyor belt. The result of sintering is to leave the corresponding trace on the bonding surface of CuAl2O3.
High temperature annealing and oxidation will accompany the grain growth of copper. In the subsequent sintering process, the grain will continue to grow, which brings adverse effects on the mechanical properties and surface treatment of copper. The copper surface grain produced by wet oxidation is fine, which is conducive to improving the mechanical properties of copper and eliminating the traces of conveyor belt. The main difference between wet oxidation and dry oxidation is shown in the bending resistance, heat resistance cycle performance and peeling strength, and these three indicators are significantly better than dry oxidation. Wet oxidation products can better meet the requirements of bending strength and heat resistance cycle performance.

So, this is the end of this post, Best Technology specialized in fabricating ceramic PCB (including DBC, DPC, AMB, HTCC and LTCC technology) for more than 16 years, we have rich engineering team and professional sales team can provide one-stop service for you. Welcome to contact us if you have any inquiries about ceramic PCB.

Common ceramic substrate materials

Nowadays, the most commonly material in the market is oxidation material, it always used in automobile products as its wear resistance and good strength.

Besides, there are some nitrides and silicious can be used in high power products.

For a quick look, here I listed as following:

Alumina Oxide (Al2O3)
Alumina Nitride (ALN)
Beryllium Oxide (BeO)
Silicon Nitride (Si3N4)
Zirconium Oxide (ZrO2)
Silicon Carbide (SiC)

Characteristics of different substrate materials

Alumina Oxide (Al2O3)

Alumina substrate characterize as a pure white substrate and the most commonly used ceramic substrate material in the electronics industry because of its high strength and chemical stability compared to most other oxide ceramics in terms of mechanical, thermal and electrical properties, and the richful source of raw materials is suitable for a variety of technical manufacturing and different shapes. The most commonly used Alumina Oxide are 96% alumina and 99.6% alumina.

96% alumina can be used to fabricate Thick Film Ceramic Circuits as it has excellent electrical insulation, mechanical strength, good thermal conductivity, chemical durability and dimensional stability. The surface roughness is generally 0.2~0.6μm, and the maximum using temperature of the substrate can reach 1600℃
99.6% alumina is the mainstay of most Thin-film electronic substrate applications, commonly used in circuit generation for sputtering, evaporation and chemical vapor deposition of metals. 99.6% alumina has higher purity, smaller grain size, and excellent surface smoothness than 96% alumina (the surface roughness is generally 0.08~0.1μm), and it can withstand maximum 1700°C temperature when applied in applications.

Alumina Nitride (ALN)

Currently, Alumina Nitride won the high attention of the public by means of two key excellent properties: one is high thermal conductivity. Alumina nitride offers a big increasing in thermal conductivity (170Wm.k), which is approximately 100-200 times than FR4 substrates did, while alumina oxide only offers 24W/m.K.

Another characteristic is silicon-matched expansion coefficient of 4.7ppm/°C 20~300°C, this makes it suitable for used in extremely harsh environments likely in high temperatures. The disadvantage is that even an extra thin oxidation will affect the thermal conductivity. Only by strictly controlling the material and process, can aluminum nitride substrate be produced with good consistency. That’s why the alumina nitride is expansive than alumina oxide.

By visually, alumina nitride has an off-white color, that give us a chance to distinguish it with alumina oxide easily.

Beryllium Oxide (BeO)

Beryllium Oxide has a high thermal conductivity than alumina, therefore, it almost used where high thermal conductivity required. But when the temperature exceeds 300°C, it drops quickly. It is not as widely used as alumina oxide or aluminum nitride, the most important thing is that its toxicity limits its development.

Silicon Nitride (Si3N4)

Silicon Nitride is a material with high fracture toughness and strong heat resistance are often used as alternative materials for modules in recent years. With strong mechanical, high temperature resistance, corrosion resistance and wear resistance, it is widely used in automotive shock absorber, engine, especially automotive IGBT products, as well as traffic track, aerospace and other fields.

Zirconium Oxide (ZrO2)

Zirconium Oxide is popular as its exceptional strength, toughness, biocompatibility, high fatigue and wear resistance (15times of alumina oxide) render it optimal for dental applications.

Silicon Carbide (SiC)

The essence of silicon carbide ceramic substrate is a silicon material, which determines its high current density characteristics due to its superior thermal conductivity.

In the meantime, the higher band gap width determines the higher breakdown field and higher operating temperature of silicon carbide (SiC) ceramic circuit board.

The core advantages of silicon carbide are high temperature resistance, high pressure resistance, wear resistance, low loss and high frequency work. Therefore, it is used for products with high heat dissipation, high thermal conductivity, large current, large voltage and high frequency operation.

Send us inquiry for fabrication

At present, you should have a brief acknowledge about different ceramic substrate materials and their characteristics, and you should be able to decide which materials is most suitable for you. If you still have some concerns or different opinions about substrate for Ceramic pcb, welcome to contact us, Best Tech will offer you free advice and technical support for ceramic substrate choice.