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Why do ceramic substrates contribute to the breakthrough of 905nm lidar technology?
Friday, September 1st, 2023

LiDAR (Light Detection And Ranging, referred to as “LiDAR”) measurement is a system that integrates three technologies: laser, GPS (Global Positioning System), and IMU (Inertial Measurement Unit, inertial measurement unit), used to obtain data and Generate accurate DEMs (Digital Elevation Models). The combination of these three technologies can highly accurately locate the spot of the laser beam on the object, and the ranging accuracy can reach the centimeter level. The biggest advantage of lidar is accurate, fast, and efficient operation.

Lidar is currently widely used in the field of driverless cars and robots. It is known as the “eye” of a generalized robot. It is an active measurement device that measures the precise distance between an object and a sensor by emitting laser light.

  As an indispensable sensor for L3 and above automatic driving, lidar has significantly improved the reliability of the automatic driving system with its excellent ranging capability, high angular resolution and sensitivity to ambient light, and has become the key to improving reliability. A key element of autonomous driving systems, but its application is constrained by cost and technical challenges.

  In the past, lidar was difficult to apply to mass-produced vehicles due to its high cost. However, recently, with the continuous evolution of technology and market competition, the cost of lidar has gradually decreased, thereby accelerating its application in the field of autonomous driving.

In this evolution process, the emergence of ceramic substrates has played a vital role in the breakthrough of lidar technology – 905nm wavelength lidar has become mainstream. Traditional materials such as FR-4 and FE-3 are difficult to meet the high heat dissipation requirements of lidar, while ceramic substrates rely on their excellent thermal conductivity. For example, the thermal conductivity of aluminum nitride ceramic substrates is as high as 200W/M.K. It effectively solves the heat dissipation problem and provides a guarantee for the stability and life of the lidar.

In lidar, the transmitter is one of the links with the highest value and the highest barriers. On the transmitter side, with the rise of China’s domestic industrial chain and the adjustment of the overall technical route of the industry, among them, 905nm VCSEL laser chips and other products have achieved breakthroughs in the market and become a hot topic in the industry.

The “heart” of the transmitter is the light source. Laser transmitter is the core component of laser technology, and its composition includes laser working medium, excitation source and resonant cavity. In this system, why choose a ceramic substrate as a component? The main reason lies in its unique advantages in heat dissipation. Especially for VCSEL (Vertical Cavity Surface Emitting Laser) chips, due to their low power conversion efficiency, the problem of heat dissipation is particularly prominent. The application of ceramic substrates has become the best choice to solve the problem of thermoelectric separation.

The ceramic substrate has excellent heat dissipation performance and can effectively conduct the heat generated inside the laser transmitter. The high thermal conductivity of the ceramic substrate allows it to efficiently conduct heat generated inside the lidar, preventing performance degradation due to overheating. In addition, ceramic materials have the advantages of high strength, hardness, thermal shock resistance, insulation, and chemical stability, which can further extend the service life of products, improve sensitivity, and enhance the response speed of lidar.

Ceramic substrates also enable high-density assembly, supporting miniaturization and integration of devices. Its stability ensures that the sensor signal is not distorted, and the matching with the thermal expansion coefficient of the chip ensures the reliability of the product in harsh environments such as high temperature, high vibration, and corrosion. In addition, the metal crystallization performance of the ceramic substrate is excellent, which ensures the stability of the circuit and further improves the quality control level of the lidar.

As a leading manufacturer of ceramic substrates, Best Technology provides a variety of ceramic substrates of different materials, including 96% alumina, 99% alumina, aluminum nitride, zirconia, silicon nitride, sapphire ceramic bases, etc. The heat dissipation properties of these different materials are different, such as aluminum nitride (AlN): thermal conductivity of 170-230 W/mK, silicon nitride (Si3N4): thermal conductivity of 20-80 W/mK, sapphire (Al2O3): thermal conductivity Coefficient 25-40W/mK.

Therefore, choosing a high-quality ceramic substrate not only helps to solve the problem of thermal and electrical separation of laser emitters, but also provides stable heat dissipation and electrical performance, providing reliable support for efficient operation and performance improvement of laser emitters. In the development of lidar technology, ceramic substrates play an increasingly important role, providing key support for performance breakthroughs and innovations in laser transmitters. We are witnessing a revolution in the auto industry brought about by China’s autonomous driving assistance systems.

If you are designing a ceramic PCB and seeking a reliable manufacturer, welcome to leave you message or contact us directly.

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What is the DBC Ceramic Copper Oxidation Technology
Monday, February 20th, 2023

DBC (Direct Bond Copper) ceramic PCB also known as DCB ceramic, which is widely used in various type of high-power semiconductor, especially in IGBT package material by means of its excellent electricity and thermal conductivity of copper and the advantages of high mechanical strength and low dielectric loss of ceramics. DBC technology uses the oxygen-containing eutectic solution of copper to directly apply it to the ceramic. The key factor in the preparation process is the introduction of oxygen element, so the copper foil needs to be pre-oxidized in advance. Do you want to know what is the copper foil oxidation technology during the DBC ceramics manufacturing? Hereinbelow, we will introduce the oxidation process for you.

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 600~800oC 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:

  1. Uneven oxidation. It will directly cause sintering defects during sintering, and the peeling strength will change greatly.
  2. 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.
  3. 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.

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Laser drilling and cutting in the production process of ceramic circuit boards
Monday, July 12th, 2021

In the ceramic circuit board processing and production process, laser processing mainly includes laser drilling and laser cutting.

Ceramic materials such as alumina and aluminum nitride have the advantages of high thermal conductivity, high insulation and high temperature resistance, and have a wide range of applications in the fields of electronics and semiconductors. However, ceramic materials have high hardness and brittleness, and its molding and processing are very difficult, especially the processing of micropores. Due to the high power density and good directivity of the laser, lasers are generally used to perforate ceramic plates. Laser ceramic perforation generally uses pulsed lasers or quasi-continuous lasers (fiber lasers). The laser beam is focused on On the workpiece placed perpendicular to the laser axis, a laser beam with high energy density (105-109w/cm2) is emitted to melt and vaporize the material. An air stream coaxial with the beam is ejected by the laser cutting head to remove the melted material from The bottom of the incision is blown out to gradually form a through hole.

Due to the small size and high density of electronic devices and semiconductor components, the precision and speed of laser drilling are required to be high. According to the different requirements of component applications, electronic devices and semiconductor components have small size and high density. Due to its characteristics, the precision and speed of laser drilling are required to be high. According to the different requirements of component applications, the diameter of the micro-hole is in the range of 0.05 to 0.2 mm. For lasers used for ceramic precision processing, generally the focal spot diameter of the laser is less than or equal to 0.05mm. Depending on the thickness and size of the ceramic plate, it is generally possible to control the defocus to achieve through-hole punching of different apertures. For through-holes with a diameter less than 0.15mm, drilling can be achieved by controlling the defocus amount.

There are mainly two types method for cutting ceramic PCB: waterjet cutting and laser cutting. Currently, fiber lasers are mostly used for laser cutting. Fiber laser cutting ceramic circuit boards has the following advantages:

(1) High precision, fast speed, narrow cutting seam, small heat-affected zone, smooth cutting surface without burrs.

(2) The laser cutting head will not touch the surface of the material and will not scratch the workpiece.

(3) The slit is narrow, the heat-affected zone is small, the local deformation of the workpiece is extremely small, and there is no mechanical deformation.

(4) The processing flexibility is good, it can process any graphics, and it can also cut pipes and other special-shaped materials.

Al2O3 PCB with drilling
AlN PCB with drilling

 Under the development trend of light and thin, miniaturization, etc., the traditional cutting processing method has not been able to meet the demand due to the insufficient precision. Laser is a non-contact processing tool, which has obvious advantages over traditional processing methods in cutting process, and plays a very important role in the processing of ceramic substrate PCB.

Please contact sales@bestpcbs.com if you want to know more ceramic PCB.

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The technology and application of DBC ceramic PCB
Thursday, June 17th, 2021

DBC means direct bonding copper, it is a ceramic surface metallization technology.

The copper is bonded on Alumina, Beryllium Oxide and Aluminum Nitride, Packaging applications for power electronic modules, semiconductor refrigeration and LED devices are widely used.

DBC-Ceramic-PCB

96% Al2O3 has good insulation, good chemical stability, high strength, and low price. It is the preferred material for DBC technology, but the thermal conductivity of aluminum oxide is low, and there is a certain thermal mismatch with the thermal expansion coefficient of Si.

BeO is a good ceramic material used in DBC technology. It has high low-temperature thermal conductivity. It can be used for medium and high power devices. In the application field and process, the toxicity caused by it should be properly protected.

AlN material is non-toxic, moderate dielectric constant, thermal conductivity is much higher than aluminum oxide, close to beryllium oxide, and thermal expansion coefficient close to SI. All kinds of chips and high-power devices can be directly attached to the AlN substrate. No transition layer of other materials is used. The prospects currently used in DBC technology are very promising.

There is no any layer between the metal and ceramic substrate, so the thermal diffusion ability is strong; the contact resistance is also low, which is conducive to the connection of high-power and high-frequency devices.     

The linking temperature is lower than the melting point of copper, and the DBC substrate maintains a stable geometric shape during the connection process. In some cases, the copper foil can be made into the required shape before the linking, and then the DBC preparation process is performed, eliminating the need After connecting the etching process.

The copper conductor part has a very high current-carrying capacity, so it has the ability to reduce the size of the intercepting medium and increase the power capacity.

If you want to know more about DBC ceramic PCB, please feel free to contact sales8@bestpcbs.com

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Do the vias can be filled for ceramic PCB?
Friday, November 13th, 2020

As everyone knows for FR4 PCB, people like the vias to be tented or filled for some special applications.
Ceramic PCB is more and more popular because of the thermal conductivity is very high and very good for heat dissipation. Most of customers are going to make the PCB with ceramic material, includes Al2O3, AlN, BeO or Si3N4, etc.
So do the vias can be filled for ceramic PCB becomes the frequently asked questions (FAQ).
The answer is YES.
So what’s the material can be filled in vias for DBC/DPC alumina PCB/ Aluminium Nitride PCB?

The material can be solder mask, Dow Corning 1-4173 and copper/Cu.
Normally, customers want the vias/holes to be filled with copper.
Because copper can fill the vias very well and it is easier to do and it looks very good. Please see below photo.
The left one with filling with copper, the right one without filling copper

Why you need to fill the vias with copper?
1.Becuase if let the vias open, they will allow solder to flow through to opposite side of PCB during reflow, this causes bridging under components.
Filling the open vias/holes with copper can prevent from the solder pates into the vias.
2.If you need to pull vacuum around them and a hole would compromise that, so need to fill the vias.
There are also other purposes for filling the vias, if you need such ceramic board with filling the vias, please contact Coco in Best Technology sales@bestpcbs.com

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