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What Are Differences of ENIG VS ENEPIG in PCB Manufacturing – Series 1
Tuesday, January 2nd, 2024

Surface treatment also called surface finishing, it is a protective layer that through coating a layer of metal organic material on the surface of printing circuit boards (PCBs). Apply a layer of surface treatment enable to protect pads from scratches and oxidation, as well as improve the solderability of components mounting. ENIG and ENEPIG are the two common high-reliable surface finishing types in the circuit board manufacturing, they are not only for FR4-PCB, but also available in ceramic PCB, flex circuits and rigid-flex PCB. Today, Best Team would like to sharing information about ENIG and ENEPIG, and explore the differences between them.

(Assembled_PCB)

How to Select the Right Surface Treatment for Your PCB?

With the rapid development of electronics, there are various of PCB types that can be used in electronic devices, and at the same time, there are also increasingly more surface treatment technics available for selection. Until now, the common surface treatments are OSP, HASL, Immersion Silver, Gold Plating, ENIG and ENEPIG. Each of these surface treatments has its own advantages and disadvantages, so it is necessary to choose the most suitable one for a particular application. The selection of surface finish needs to take into account factors such as cost, application environment, fine-pitch components, the use of leaded or lead-free solder, operating frequency, shelf life, drop and impact resistance, volume and throughput, as well as thermal resistance.

With PCBs trending towards micro-vias and finer traces, and the drawbacks of HASL and OSP, such as flatness and flux elimination issues, becoming more pronounced, the demand for surface treatments like ENIG continues to grow. In addition, black pad is a major weakness of ENIG while ENEPIG enable to solve it very well, making it a preferred choice for those PCBs need to wire bonding.

What is the ENIG Surface Treatment?

ENIG, its full name is Electroless Nickel Immersion Gold, is also known as chemical gold or immersion gold in the electronics industry. This type of surface treatment provides two metal layers—gold and nickel—that manufacturers deposit them on the surface of PCB pads sequentially. This surface finish is a selective surface finish, meaning that certain specific pads may have ENIG surface finish, while others may have different types, such as OSP, HASL, or immersion tin. Here are the main processes of the ENIG coating:

  • Copper activation

In this step, manufacturers will active the copper layer through cleaning process, this way can help to remove the dust and oxides residual on the surface, but also remove any gases or air trapped in the perforations (holes) of the PCB by wetting the surface. Next, micro-etching the PCB surface using substances like hydrogen peroxide or sulfuric acid.

  • Electroless nickel

This process is to coat a layer of nickel on the active copper layer by electroplating. The nickel layer serves as a protective layer or inhibitor, which prevent the copper reactive with other elements.

  • Immersion gold

Immersion gold is the last step of whole ENIG process, immersing the PCB into a mixture, oxidizing the nickel surface, generating nickel ions, and then reducing gold from the mixture. The reduced gold forms a metallic coating to protect the nickel surface. This is the whole process of coating ENIG surface treatment.

(PCB_with_ENIG_surface_treatment)

Advantages of ENIG

  • Surface flatness – good for fine-pitch and small size components like BGA.
  • Suitable for press-fit components since it provides a reliable connection for electrical testing.
  • Suitable for wire bonding and gold-fingers connectors.
  • Cost-effective compared with ENEPIG

Disadvantages of ENIG

  • Black pad issues.
  • Varied coating thickness because of the uncontrolled nickel plated and immersion gold.
  • Poor wettability during PCB assembly.

All in all, ENIG is a good option if you want to mount fine-pitch components on the PCB surface or if you are considering its use in plug-and-pull devices such as WIFI interfaces. In our next blog, we will introduce ENEPIG surface treatment, including its pros & cons and the differences between ENIG and ENEPIG. Pay attention to our news or contact us directly if you want to know more.

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Do You Know How Does the ENEPIG Working for Wire Bonding Circuit Boards?
Friday, November 10th, 2023

The electronics industry has continuously pursued smaller and faster electronic products with increased functionality. To meet these demands, the electronic packaging industry has focused on developing more advanced packaging methods, aiming to increase the density of components on a circuit board while integrating multiple functions into a densely package.

The increasing density of packaging and interconnection has driven the progression of assembly methods from through-hole technology (THT) to surface-mount technology (SMT). Additionally, the use of wire bonding to connect chips to substrates has become more prevalent. The adoption of smaller interconnect pitches and chip-scale packaging (CSP) has further increased component density, while multi-chip modules (MCM) and system-in-package (SiP) have enabled the integration of more functions on a single package.

This post describes the key factors affecting the reliability of interconnections, with a particular focus on the specific properties of surface-treated wire bonding, emphasizing the selection of wire bonding surface treatments.

Selection of Surface Treatment for Wire Bonding

While electroless nickel gold provides excellent performance for wire bonding, it has three main drawbacks that hinder its application in cutting-edge technologies:

1. The relatively high demand for gold layer thickness leads to lengthy process costs.

2. Thick gold layers are prone to the formation of weak tin-gold intermetallic compounds (IMC), reducing the reliability of solder joints. To enhance solder joint reliability, alternative surface treatments may be used, but this increases additional process costs.

3. The electroplating process requires the use of electroplating lines, limiting the design freedom and wiring density of the packaging substrate.

The limitations posed by electroplated nickel-gold provide an opportunity for the adoption of chemical plating. The techniques of chemical plating include Electroless Nickel Immersion Gold (ENIG), Electroless Nickel Electroless Gold (ENEG), and Electroless Nickel Palladium Immersion Gold (ENEPIG).

Among these three options, ENIG is generally unproblematic due to its lack of high reliability in gold wire bonding properties (although it has been used in some low-end consumer products). On the other hand, ENEG shares the high production cost and presents complex challenges in terms of the manufacturing process, similar to electroplated nickel-gold.

ENEPIG was initially introduced in the late 1990s, its market acceptance was delayed until around the year 2000 due to fluctuations in palladium metal prices (which were inflated to unreasonable levels around 2000). However, ENEPIG can meet the requirements of many new packaging applications, providing reliable performance and conform to lead-free/ROHS requirements, with a recent strong surge in market demand.

In addition to the advantages in packaging reliability, the cost of ENEPIG is another benefit. With the recent rise in gold prices surpassing US$800/oz, it becomes challenging to control costs for electronic products requiring thick gold plating. The price of palladium (US$300/oz), relative to gold, is less than half, making palladium a cost-effective alternative with surface-related advantages.

Comparison of Surface Treatments

Up to now, for printed circuit boards accommodating fine-pitch QFP/BGA components, there are primarily four lead-free surface treatments:

Immersion Tin (IT)

Immersion Silver (IAg)

Organic Solderability Preservatives (OSP)

Electroless Nickel Immersion Gold (ENIG)

The table below compares these four surface treatments with ENEPIG. Among these surface treatments, none can simultaneously meet all the requirements of lead-free assembly processes, especially when considering multiple reflow experiences, pre-assembly shelf life, and gold wire bonding experiences. In contrast, ENEPIG offers good shelf life, solder joint reliability, gold wire bonding capability, and can serve as a touch button surface, providing surface-related advantages. Moreover, in the final gold replacement deposition reaction, the chemical palladium layer in ENEPIG works to protect the nickel layer, avoiding excessive corrosion during gold replacement.

(Table 1 – Comparison_of_Different_Surface_Treatment_Performances)

What Are Advantages of ENEPIG?

ENEPIG has several crucial advantages, demonstrating reliable solderability and gold wire bonding concurrently. The key benefits are outlined as follows:

  • Prevention of “Black Nickel Problem” – The absence of gold replacement attacking nickel on the surface prevents interfacial corrosion.
  • The chemical palladium layer acts as a barrier, preventing copper from diffusing to the surface, ensuring satisfactory solderability.
  • Palladium layer enable to completely dissolves in the solder, preventing the exposure of a high-phosphorus layer at the alloy interface. After the dissolution of the chemical palladium layer, the chemical nickel layer is revealed, forming a satisfactory nickel-tin alloy.
  • Capability to Withstand Multiple Lead-Free Reflow Cycles
  • Excellent Gold Wire Bonding Properties

These advantages make ENEPIG a preferred choice in various applications, ensuring reliable performance in both soldering and wire bonding processes while offering cost efficiency. As a one-stop PCB supplier in Asia, Best Technology possesses advanced technology and high-tech manufacturing equipment that can meet the “multi-variety, small volume, high quality, strong capability, short delivery” requirements. Welcome to contact us if you are going to find a reliable circuit board manufacturer.

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How Can I Reduce and Optimize the Cost of My PCB in A Best Way? – Series 2
Saturday, October 28th, 2023

At our latest blog, may the readers have understood the factors that will affect the PCB price, or maybe one of your have put it into practice that get a price lower than your budget. However, people are always not satisfied by the existing situation. If this is bother you as well, keep reading since this time we are going to sharing some useful tips that enable to optimize your PCB price until to the best.

  • Reduce board complexity

It can be said that try to simplest your design/layout and make it easy to fabricate is the simplest way to reduce your PCB cost. The more complex and irregular the forms, the higher the cost. Just remember: for every circuit board, no need to maintain a fancy diagram to demonstrate its excellence, perform functionality correctly is enough.

  • Design it in right size and thickness

Design your board in right size doesn’t means make it smaller as possible. You must know, if your design is complex and layouts are density, that means maker need to spend more time to assemble them. Highly compact sizes are always expensive, don’t skimp when it counts. Otherwise, more money will be spent to afford what you saved.

And in theory, the more layers and thickness the board, the more cost that manufacturer spend. Numerous layers in the PCB will have an influence for holes and diameters. It is recommended that if thinner thickness is enough, then just do it. 

  • Shapes, holes and rings should be regularly

Normally, keep the PCB as square or rectangular shapes is cheaper than irregular shapes like pentagon.  And large holes and rings enable to smooth the production run and easy to create. For smaller holes and rings means the driller must be smaller and delicate control.

  • Consider volume and choose manufacturer

In our last blog, we emphasize manufacturers will set a minimum order quantity (MOQ), it is common in this industry. So, consider your volume and check multiple quantities before ordering can help to recognize which one is the most cost-effective.

During the evaluation period, talk to your suppliers as soon as possible, knowing more about the material specifications, technical and PCB tolerances. A wrong choice will lead to much time waste and some unnecessary cost. This is we call “trial and error cost”. Try to make all things are clear and correct before production.

  • Pick the best vias

There are totally three types of vias in PCB: though-hole, blind, buried. The through hole can be passed through the whole board, while blind vias is created from top or bottom side to the middle of the board without through to bottom or top side. Buried vias, just as its names, it is buried inside the boards and we can’t see it by naked eyes.

Obviously, through hole is cost performance than other two vias, try to use more instead of blind or buried vias enable to decrease your cost. In additionally, blind and buried vias are always necessary in HDI PCB and RF board, otherwise, you don’t usually use them.

  • Make sure all SMT components on the one side

Trying to make all the surface mounted (SMT) components on the one side of circuit board if possible. In this way, assembler can finish the SMT process in one-time, so that can save much manufacturing time and cost. But if the components are distributed on both sides, it is needed to assemble two times, that is top side first – bottom side second (or sometimes bottom first).

  • Select easily replaceable component parts

It is assumed that one of part on your circuit becomes obsolete, then you must search for replaceable part or update your design if you would like to continuedly use this board. As an extensive experienced PCB manufacturer, we strongly recommend that select components that has standard dimension, so that it is easy to match alternative one.

In addition, visit some manufacturer’s website carefully to see if any components are marked as “obsolete” or “not recommended for new designs” before finishing your design. This enables to avoid secondary update.

  • Follow manufacturer’s PCB fabricate standards

Understand and follow manufacturer’s fabricate standards can keep your unit PCB price in a relative lower cost. When designing a new project, please make sure to following below tips.

  1. Use standard stack-up with standard materials.
  2. Design 2-4 layers PCB if possible.
  3. Keep your minimum line width and spacing within the standard spacing.
  4. Avoid adding extra special requirements as much as possible.
  • Use SMT components as possible

Choose surface mounted (SMT) components instead of through hole (THT) component whenever possible. SMT and THT are almost treated as separated manufacturing processes. Hence, if all the THT components can be replaced by mounted parts, the THT process will be eliminated completely. It is not only decreasing the manufacturing cost, but also reducing delivery time. Of course, it is not always possible, but it’s worth trying.  

Whatever decisions you make, the best solution is to consult and discuss with your suppliers. They be always to give you the best one that can save your money and meet your requirements as well. Meanwhile, if you don’t believe the suppliers, you are welcome to reach us. We promise that we can give you a most favorable price and high-quality product.

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What Factors Affect the PCB Board Price? How to Keep the Best Price? – Series 1
Saturday, October 28th, 2023

For each development engineer or purchaser, how to keep the cost within the budget is a most irksome and irritating assignment while the PCB has the good quality and enable to perform desired function. They need to understand the computation rule and calculate the developing cost. So, it is worth to knowing the factors that affect the printed circuit board price, and it is a must learn course for every engineers. Herein, Best Technology is going to dissect the factors affect the cost of PCB, let’s move on!

What affects the cost of a PCB?

Drives the cost of PCBs are numerous, we can see from the PCB itself, for example, circuit board substrate materials, the external factors such as the manufacturing difficulties, the whole order quantities and some other special requirements that from designers.

Here, we listing some basic parameter factors which drives the whole cost of a PCB.

  • PCB substrate material

The substrate of PCB board refers to the material used in the non-conductor part of the circuit board, mainly FR4, glass fiber, epoxy resin, polyimide, copper, aluminum and so on. In the PCB manufacturing, glass fiber is widely used in the manufacture of double-sided circuit board and multi-layer board, while epoxy resin and polyimide are used in the manufacture of high-density multi-layer board. Among them, copper substrate is most expensive material. No matter what kind of materials, all of them shall be calculated according to the real-time international price.

  • PCB size (panel and single pcs)

PCB size will determine the price of PCBs, this is for sure. Generally speaking, with a same number of PCB layers, the smaller the PCB size, the cheaper the cost. Because during calculating cost, vendors will consider the utilization rate of raw materials. Make sure the highest utilization, the cost for both purchaser and vender will be best. The raw material of PCBs is commonly 1200mm*1200mm, or 1220mm for special specifications, when the utilization achieves 90% or above, this is the best.

So, how to improve the utilization of raw materials? Normally, manufacturers will optimize the working files (WF) from single size to panel size, and then material will be cut according to the panel files. But if the panel size is not suitable, then there will be a lot of waste edges of raw material in the cutting process, and generally this will be added into your PCB price. So that the unit PCB price will be more expensive. In another word, if you PCB size is well-suited, then it is good for PCB manufacturer and yourself. And at this time, the utilization will be the highest and your PCB cost is the cheapest as well.

  • Line width/spacing

To a certain extent, as long as you are following the PCB design rules, the PCB price will not too high. However, if your design is complex and the line width is extreme thin, then the price will increase since it is difficult to control during manufacturing.

  • PCB layers

According to the IPC standard, PCBs can be classified to single-layer PCB, double sided PCB and multilayer PCB. For layer count over than 2 layers, we called it as Multilayer PCBs, such as 4 layers PCB, 6 layers PCB. For FR4 PCB, we can make up to 32layers.

Due to the manufacturing process and some unpredictable assembling cycles, the more the layers, the more expensive it is. (The price of single side PCB is the similar to double sided PCBs.)

  • Solder mask ink color

In the past, it is no doubt that you will spend more if you want every color expect green. But now things are changeable. Most colors are available at no or very little extra cost, which usually only occurs for unique requests such as matte tones.

  • PCB copper foil thickness

The weight of copper foil depends on the successful utilization of the material. Thicker copper is more expensive and comes with additional manufacturing difficulties and expenses. You may also have to fill the holes with copper foil to connect layers. In addition, heavier copper means you need to spend more cost in shipping. Let’s take a simple example, for aluminum core PCB and copper core PCB, in the same volume and quantities, copper core PCB stands out for expensive shipping cost since it has thicker copper and heavier weight.

  • PCB surface treatment

Surface treatment is a method that using for protecting the surface from corrosion and improve the solderability. Usually, in consideration of environmental friendliness, vendors can use a couple of gold or silver to achieve further safety for use in some applications.

The commonly used surface treatment methods include OSP, IMMERSION SILVER, ENIG, ENEPIG and HASL (LF). Among them, the price is ENEPIG>ENIG>IMMERSION SILVER>OSP>HASL. You can calculate the PCB board price according to the surface treatment method and gold thickness.

  • Quantity and lead time

When developing a new project, almost of companies would like to make prototypes first and ask for a sample quotation. However, some PCB manufacturers will set the minimum order quantity, the smaller the quantity, the higher cost the PCB board. Please make sure to check the price for different amount before placing an official order.

Meanwhile, the delivery time request also will affect the whole price in a certain. And certainly, the price of quick turn order and expedited service will higher than normal order.

  • Other special requirements (impedance, IPC standard)

To ensure the stable transmission of circuit board signals and improve the quality of signal transmission, designers and engineers will ask for impedance control for the traces. This can be seen as special requirements, so it will add a few extra prices. And the required IPC Criteria is a factor as well. Normally, if customer does not have other request, we will default use IPC class II. III level will more expensive.

Above all are the mainly factors that affect the price composition for a printed circuit board. When evaluating your PCB cost, making them in your consideration is best.

PCB and PCBA supplier that can save cost for you – Best Technology

When you are seeking for a reliable PCB and PCBA supplier, I would like to recommend Best Technology to you. Best Tech offers one-stop service including raw material purchasing, PCB making, components searching, assembly, box building and package out of warehouse. What we can provide is not limited to PCB, but also metal core PCB, ceramic PCB, flexible PCB, rigid flex PCB, special PCB like HDI PCB, heavy copper PCB, extra thin PCB and so on. During the 17 years, the Best Technology company has served include medical industry, consumer electronics, new energy, automotive electronics, aerospace, military and others.

Could it be said that you are searching for a PCB supplier that can provide favorable price that lower than market? If this is true, please go ahead and reach us today, let’s talk about more PCB information right now and start our business trip together. We promise, when you decide to take the first step, and we’ll take the remaining 99 steps.

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What Is Ceramic Metallization Technology? – Series 1
Saturday, October 7th, 2023

Due to the different surface structures of ceramic susbtrates and metal materials, welding/soldering often cannot wet the ceramic surface or form a strong bond with it. Therefore, the joining of ceramics and metals is a special process, which called as metallization.

What Ceramic Metallization Technology Is?

Ceramic metallization refers to the process of firmly attaching a thin layer of metal film to the surface of a ceramic material to achieve a bond between the ceramic and metal. There are various methods for ceramic metallization, commonly including molybdenum-manganese (Mo-Mn) method, directly copper plate (DPC), directly bonded copper (DBC), active metal brazed (AMB) method and more.

Which Ceramics Can Be Used Metallization Technology?

At present, there are four common ceramic substrates that always used for metallization, they are BeO, Al2O3, AlN and Si3O4. But different ceramic has different characteristics, so its metallization method also is different.

  • BeO Ceramic

The most common method for metallizing BeO ceramics is the Mo-Mn method. This involves applying a paste-like mixture of pure metal powders (Mo, Mn) and metal oxides to the ceramic surface, followed by high-temperature heating in a furnace to form a metal layer.

  • Al2O3 Ceramic

The primary metallization methods for Al2O3 ceramics are DBC and DPC. This method involves placing a treated copper foil on the surface of Al2O3 ceramics, introducing an inert gas with a certain oxygen content, and then heating. During heating, the copper surface undergoes oxidation, and when the temperature reaches the eutectic liquid phase region, a eutectic liquid phase is formed, wetting both Al2O3 ceramics and copper, achieving a tight bond. In a chemical sense, the adhesion used by DBC is stronger than DPC since it has thicker copper.

  • AlN Ceramic

Common methods for AlN ceramics include DBC and Active Metal Brazing (AMB). DBC is similar to the method used for Al2O3 ceramics but requires pre-oxidation treatment of AlN ceramics since AlN is a non-oxide ceramic. AMB involves connecting AlN ceramics and copper foils using active metal brazing materials, often Ag-Cu-Ti alloys.

  • Si3N4 Ceramic

Si3N4 ceramics cannot be directly metallized using the direct copper plating method because they do not generate an oxide layer on the surface like AlN ceramics. Si3N4 ceramics are typically connected to metals using the AMB method, where chemical reactions between Si3N4 and active metals (Ti, Cr, V) form continuous nitride layers at the interface.

What is the Metallization Temperature?

During the metallization process, the sinter temperature should be controlled strictly. Normally, it can be divided into four ranges:

  • Ultra-High Temperature (Above 1600°C):

This temperature range is reserved for specific applications where extreme heat resistance is required.

  • High Temperature (1450°C to 1600°C):

High temperatures are essential to ensure that the glass phase spreads and migrates effectively, enabling a strong bond. However, excessively high temperatures can lead to reduced metallization strength.

  • Mid-Temperature (1300°C to 1450°C):

This range is chosen to balance the need for effective metallization with the preservation of material properties.

  • Low Temperature (Below 1300°C):

Lower temperatures are used when the primary concern is avoiding thermal stress on the materials involved.

Proper high sintering temperature is necessary, otherwise, the glass phase will not spread and migrate. But if the temperature is too high, the metallization strength will be poor. So, choose a suitable temperature is important to make sure the metallization effective.

This is all the information about metallization technology, in our next blog, we will delve into what factors will affect the metallization. If you are interested in metallization or other technologies about ceramic circuit boards, please leave your message and keep your eyes in Best Technology website.

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What Is The Difference Between Thin Film and Thick Film Ceramic PCBs?
Monday, September 25th, 2023

We know due to the rapid development of electronic devices, Ceramic circuit boards have gradually developed into an ideal packaging substrate for a new generation of integrated circuits and power electronic modules. Among them, thick film ceramic substrate and thin film ceramic PCB are the most popular ceramics that be used in package, because they are made by metallization process.

Why use film technology?

Compared with three-dimensional ceramic materials, film has relatively thin thickness and small size, it can be regarded as a two-dimensional structure. Thick film is made by printing process, the thick film can be made independently and the thickness is usually 10~25μm. Thin film is formed by the composition of the conductor materials and it was sputtering on the ceramic substrate directly. Normally the thickness of thin film is equal or less than 1μm. If the metallization thickness between 1μm to 10μm, then we called it as Directly Plated Copper (DPC) ceramic circuit board.

(ceramic_pcb_with_green_glass_glaze)

Thick Film Technology

Thick film technology is a method of direct deposition of slurry on substrate through screen printing technology, and sintering at high temperature to form conductive traces and electrodes. After the material is sinter at high temperature, it will form a strong adhesion film on the ceramic circuit board, and after repeated many times, it will form a multi-layer interconnected ceramic circuit board with resistor or capacitor. The thick film manufacturing process is more easier than thin film.

(Simply_process_for_thick_film_ceramic)

Thin Film Technology

Thin film ceramic PCB is a chip manufacture technology, which is the main method of metal film deposition in microelectronics fabrication. It was made through evaporation and PVD process firstly to deposited a 200-500nm copper layer as the seed layer. Then using electroplating process to increase the copper foil to required thickness. Finally through stripping and etching to generate the circuits. Thin film ceramic circuit is widely used in LED package fields because its fine traces, high accuracy and heat dissipation.

(Manufacturing_process_of_thin_film_ceramic)

Thin film and Thick film ceramic PCB comparison

In addition to the technology manufacturing difference, their performance and limitations also is different. Here we summarized in below table:

TechnologyThick FilmThin Film
Conductor thick10-25um<=1um
Manufacture processScreen printing, sinterPVD, DES
TCR(50-300) *10-6/C(0-50) *10-6/C
CostRelatively LowHigh for prototype
Line widthThicker line widthFine traces, suitable for RF
Bonding abilityNot suitable for bondingGood for wire bonding
ResistanceAvailableNeed mount resistors
Solder maskAvailableAvailable

Application difference between Thin film and Thick film ceramic PCB

The applications of thin film and thick film also are different because of their different features. Thick film ceramics are widely used in high power devices such as automotive field, power electronics, aerospace due to its ability to handle high current and voltage. Thick film enables to provide excellent thermal management and can dissipation heat effectively. Thin film ceramic PCBs trend to micro-electronics and RF devices because of its fine lines, low resistance, and high-frequency performance.

Each technology has its unique advantages and limitations, it needs to be properly used to make it suitable for different electronic devices and industries. Choose the right ceramic PCB substrate for laymen is a big challenge, so seeking for a reliable supplier is important. Best Technology engaging ceramic circuit board manufacturing for over 10 years. And our core engineering team are deep in this industry for more than 20 years, we are so confident that we can provide the best solution for you. If you are interested in this, welcome to contact us at sales@bestpcbs.com.

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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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Can I Design Via Holes in Thick Film Ceramic Boards?
Tuesday, April 18th, 2023

May some engineers or designers who be interested in thick film ceramic circuit are curious about can thick film ceramic boards design with via holes like FR4 PCB? Herein, we will explore the feasibility of using thick film ceramic boards for via holes, including the materials and processes involved, as well as the advantages of this approach.

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!

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“TEN Q & A” about Ceramic Printed Circuit Board
Monday, February 27th, 2023

Q1: What do the abbreviations DBC and AMB stand for?

A: DBC means “Direct Bond Copper” while full name of AMB is “Active Metal Brazed”. Both abbreviations refer to bonding technology of attaching a relatively thick copper (generally more than 0.2mm) on the ceramic substrates. These two technologies can be used to fabricate metalized ceramic substrates.

Q2: What is the mainly difference between DBC and AMB?

A: The mainly difference is AMB need to braze the copper to a ceramic board by active metal while DBC can directly connect the copper and substrate without any additional materials.

Q3: Which kind of ceramics are suitable for DBC and AMB?

A: DBC technology is suitable for oxide ceramics such as Al2O3 and ZTA. Non-oxide ceramics must be oxidized before they can be bonded to copper by DBC technology. ALN can be made into DBC or AMB ceramics, but Si3N4 only can be used as AMB substrates.

Q4: What is the function of metalized ceramic PCB?

The metallized ceramic substrate needs to carrier and interconnect multiple power semiconductor devices. The resulting electronic components are called power modules or multi-chip packages, most commonly LED packages or semiconductor packages. 

Q5: Does AMB can be used with oxide ceramics?

A: Yes, but the effective of DBC technology is better and the cost is relatively lower.

Q6: What is the most important performance need to be considered when design a new ceramic PCB?

A: It depends on the end application of product will be used in. Ceramics are chemically inert substances that are resistant to corrosion, moisture, and high temperatures, making them preferable to organic dielectrics that degrade in corrosive environments. Electrical, thermal and mechanical properties are equally important in the design of a new substrate. Dielectric strength is an important factor to meet the isolation requirements, which should be set according to the standards, specifications and regulations of the target application. Low thermal conductivity is not conducive to the heat transfer between the chip and the surrounding environment. The bending strength and fracture toughness play an important role in prolonging the service life of the substrate under thermal-mechanical stress.

Q7: How to choose a suitable substrate?

A: First, the heat dissipation of power semiconductor devices should be understood. Then, based on the chip and the ambient temperature, the required substrate thermal resistance is calculated. However, the combination of copper and ceramic may not always achieve the desired thermal resistance.  For one thing, the isolation voltage determines the minimum thickness of the ceramic. On the other hand, the thickness ratio of copper to ceramic has a great effect on the reliability. Finally, the set of applicable standards will be very limited.

Q8: Are DBC and AMB substrates suitable for high voltage applications?

A: The DBC substrate is ideal for applications with operating voltages up to 1.7 kV.  For higher operating voltages, a thicker ceramic layer is required to meet the relevant isolation requirements.  Silicon nitride (ALN) is often used because its high thermal conductivity offsets the increased thickness. In addition, resistance to partial discharge is particularly important in this application. Thus, AMB is superior to DBC techniques for this purpose unless the interfacial gap between copper and ceramics can be eliminated.

Q9: Are DBC and AMB substrates copper plated only on both sides?

A: No, both of two technologies can plate copper only on one side. But this is not a standard combination of materials, however, because the resulting flatness of the substrate is critical in multiple applications.

Q10: What are the shapes of substrates?

A: The rectangle is the cheapest and most common shape to produce. Other shapes are also available, but may incur additional production costs.

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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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