LED chip flip process principle and development trend

The reason why wafer loading is called "flip-chip" is compared to the traditional wire bonding method (WireBonding) and post-balling process. Conventionally, the electronic surface of the wafer connected to the substrate by metal wire bonding is facing upward, and the electrical surface of the flip chip is facing downward, which is equivalent to turning the former over, so it is called "flip-chip".

The reason why wafer loading is called "flip-chip" is compared to the traditional wire bonding method (WireBonding) and post-balling process. Conventionally, the electronic surface of the wafer connected to the substrate by metal wire bonding is facing upward, and the electrical surface of the flip chip is facing downward, which is equivalent to turning the former over, so it is called "flip-chip".

The essence of flip chip is that on the basis of the traditional process, when the light-emitting area and the electrode area of ​​the chip are not designed in the same plane, the electrode area is mounted toward the bottom of the lamp cup, and the process of soldering the wire can be omitted. However, the precision of the process of solid crystal is high, and it is generally difficult to achieve a high yield.

The required conditions for flip chip:

1 The substrate material is silicon; 2 electrical surface and solder bump are on the lower surface of the component; 3 after the substrate is assembled, an underfill is required.

The advantages of flip chip compared to traditional processes:

A GaN-based LED structure layer is grown on the sapphire substrate by MOCVD technology, and light emitted from the P/N junction light-emitting region is emitted through the upper P-type region. Due to the poor conductivity of P-type GaN, in order to obtain good current expansion, a metal electrode layer composed of Ni-Au is formed on the surface of the P region by evaporation. The lead of the P region is taken up through the metal film of the layer. To achieve good current spreading, the Ni-Au metal electrode layer should not be too thin. For this reason, the luminous efficiency of the device is greatly affected, and it is usually necessary to take into account both the current expansion and the light extraction efficiency. However, in any case, the presence of the metal film always deteriorates the light transmission performance. In addition, the presence of wire bond pads also affects the light extraction efficiency of the device. The structure using GaN LED flip chip can fundamentally eliminate the above problem.

Inverted LED chip technology industry application analysis:

In recent years, countries around the world such as European countries, the United States, Japan, South Korea and China have implemented LED lighting related projects. Among them, the “Ten Cities and Ten Thousand Miles” program promoted by China is the most eye-catching. Street lamps are an indispensable part of urban lighting. Traditional street lamps usually use high-pressure sodium lamps or metal halide lamps. The biggest characteristic of these two sources is that the arc tube is small in size, can produce a large light output, and has high light efficiency. . However, such light sources are used in road lamps. Only about 40% of the light passes directly through the glass cover to the road surface, and 60% of the light is reflected by the lamp reflector and then emitted from the lamp. Therefore, there are basically two shortcomings in the traditional lamps. One is that the illumination in the direct illumination direction is very high, and the secondary road can reach 50Lx or more. This area is obviously over-illuminated, and the illumination at the intersection of the two lamps is only It is 20%-40% of the illumination at the center of the lamp, and the light distribution uniformity is low. Second, the reflector efficiency of such lamps is generally only 50%-60%, so there is a large amount of light loss during the reflection process, so The traditional high-pressure sodium lamp or metal halide lamp street lamp has an overall efficiency of 70-80%, low uniformity, and excessive waste of illumination. In addition, high-pressure sodium lamps and metal halide lamps usually have a service life of less than 6000 hours and a color rendering index of less than 30; LEDs have significant advantages such as high efficiency, energy saving, long life (50,000 hours), environmental protection, and high color rendering index (>75). How to effectively apply LED to road lighting has become the hottest topic for LED and street lamp manufacturers. Generally speaking, according to the use environment of the street lamp, there are strict requirements on the optical design, life support, dustproof and waterproof capability, heat dissipation treatment, and light effect of the LED. As the core of LED street light, the manufacturing technology of LED chip and the corresponding packaging technology jointly determine the future application prospect of LED in the field of lighting.

1) LED chip's luminous efficiency is improved

The improvement of the luminous efficiency of LED chips determines the energy-saving ability of LED street lamps in the future. With the development of epitaxial growth technology and multi-quantum well structure, the internal quantum efficiency of epitaxial wafers has been greatly improved. How to meet the standard of street lamp usage depends largely on how to extract the most light from the chip with the least amount of power. Simply put, it is to reduce the driving voltage and increase the light intensity. LED chips of traditional dressing structure generally need to be coated with a translucent conductive layer on p-GaN to make the current distribution more uniform, and this conductive layer will partially absorb the light emitted by the LED, and the p electrode will block part of the light. Light, this limits the light extraction efficiency of the LED chip. The flip-chip LED chip can not only avoid the problem of light absorption and electrode pad shading on the conductive layer of the P electrode, but also guide the downward light by providing a low-ohmic contact reflective layer on the p-GaN surface. Up, this can simultaneously reduce the drive voltage and increase the light intensity. (See Figure 1.) On the other hand, the patterned sapphire substrate (PSS) technology and chip surface roughening technology can also increase the light extraction efficiency of the LED chip by more than 50%. The PSS structure is mainly to reduce the total light reflection efficiency of the photons in the device, and the chip surface roughening technology can reduce the light loss reflected at the interface when the light is emitted from the inside of the chip to the outside of the chip. At present, the LED chip adopts flip-chip structure and graphic technology. After 1W power chip white light package, the light efficiency is up to 134lm/W at 5000K color temperature.

2) LED chip life and reliability

Chip junction temperature and heat dissipation

The heat dissipation problem is a technical problem that needs to be solved by the power type white light LED. The quality of the heat dissipation effect is directly related to the life of the street lamp and the energy saving effect. LEDs rely on electrons to generate light between energy bands, and the spectrum does not contain infrared parts, so the heat of LEDs cannot be radiated by radiation. If the heat in the LED chip is not dissipated in time, it will accelerate the aging of the device. Once the temperature of the LED exceeds the maximum critical temperature (according to different epitaxy and process, the chip temperature is about 150 ° C), it will often cause permanent failure of the LED. Effectively solving the heat dissipation problem of the LED chip plays an important role in improving the reliability and life of the LED street lamp. The most straightforward way to do this is to provide a good thermal path for heat to escape from the junction. At the chip level, the vertical and flip-chip structure has better heat dissipation than the conventional dressing structure with a sapphire substrate as the heat sink. The vertical structure chip directly uses a copper alloy as a substrate, which effectively improves the heat dissipation capability of the chip. Flip-Chip technology flips the LED chip onto a silicon substrate with higher thermal conductivity by eutectic soldering (thermal conductivity is about 120W/mK, traditional packaged sapphire thermal conductivity is about 20W/mK), chip The gold bumps and the silicon substrate between the substrate and the silicon substrate simultaneously improve the heat dissipation capability of the LED chip, and ensure that the heat of the LED can be quickly extracted from the chip.

Chip ESD protection

In addition, antistatic discharge (ESD) capability is another factor that affects the reliability of LED chips. The blue chip of the sapphire substrate has positive and negative electrodes on the chip with a small pitch. For the InGaN/AlGaN/GaN double heterojunction, the thickness of the InGaN active layer is only a few tens of nanometers, and the ability to withstand static electricity is limited. It is broken down by static electricity to disable the device. In order to prevent damage to the LED chip by static electricity, on the one hand, a production management method such as grounding the production equipment and isolating the human body static electricity may be employed, and on the other hand, a Zener protection circuit may be added to the LED chip. In the field of street lamps, the traditional chip structure ESDHBM is about 2000V. It is usually necessary to connect a Zener chip through a gold wire in the packaging process to improve the ESD protection capability, which not only increases the packaging cost and process difficulty, but also has greater reliability. risks of. By integrating the Zener protection circuit inside the silicon substrate, the antistatic discharge capability of the LED chip (ESDHBM=4000~8000V) can be greatly improved, the package cost can be saved, the packaging process can be simplified, and the reliability of the product can be improved.

3) Examples show the stability of flip chip

LED street lights are usually around 60-200W. Currently, they are mainly implemented in two ways. One is to realize high-watt by means of "modules with multiple chips in series with gold series" and "multiple LEDs connected in series through PCB". number. Regardless of the implementation method, the circuit connection between the chip and the bracket is required by wire-bonding in the packaging process, and the impact of the porcelain nozzle on the LED chip during the soldering process leads to LED leakage, soldering, etc. The main reason is that the traditional dressing and vertical structure LEDs are located on the light-emitting surface of the chip. Therefore, the frontal impact of the porcelain nozzle during the wire bonding process is likely to cause damage to the light-emitting area and the electrode metal layer. In the flip-chip structure of the LED chip, the electrode Located on the silicon substrate, the chip does not impact the wire during the wire bonding process, greatly improving package reliability and production yield.

LED chip packaging requirements

As the core device of the LED street lamp, the performance of the LED chip needs to be improved by the LED packaging process to achieve the effects of light efficiency, life, stability, optical design, and heat dissipation. Due to the different chip structure, the corresponding packaging process also has a big difference.

Light efficiency improvement

The positive and vertical structures of the chip are GaN in contact with phosphor and silica gel, while the flip-chip structure is sapphire in contact with phosphor and silica gel. GaN has a refractive index of about 2.4, sapphire has a refractive index of 1.8, phosphor has a refractive index of 1.7, and silica has a refractive index of usually 1.4-1.5. Sapphire/(silica gel + phosphor) and GaN/(silica gel + phosphor) total reflection The critical angles are 51.1-70.8° and 36.7-45.1°, respectively. In the package structure, the light emitted from the sapphire surface has a larger total reflection critical angle through the silica gel and the phosphor interface layer, and the total reflection loss of the light is greatly reduced. At the same time, the design of the chip structure is different, resulting in different current density and voltage, which has a significant effect on the light efficiency of the LED. For example, the conventional positive-loading chip usually has a voltage of more than 3.5V, and the flip-chip structure has a more uniform current distribution due to the design of the electrode structure, so that the voltage of the LED chip is greatly reduced to 2.8V-3.0V, and therefore, in the same luminous flux. In the case, the light effect of the flip chip is about 16-25% higher than that of the positive chip.

Reliability improvement

The reliability of LED is determined by LED chip, phosphor, silica gel, bracket, gold wire and other materials. The heat generated by LED chip can not be quickly exported, which will directly affect the junction temperature of LED chip and the reliability of phosphor and silica gel. At present, phosphors vary greatly depending on the system, and the high temperature resistance is also different. Generally, the phosphor starts to decay above 100-120 ° C. Therefore, how to reduce the temperature of the surface of the LED chip becomes a key factor for improving the reliability of the LED. The vertical structure chip can quickly transfer heat to the support through the metal substrate, the surface temperature of the chip is low, and the heat of the positive package chip is exported to the support through the sapphire. Since the thermal conductivity of the sapphire is low (about 20 W/mK), the heat cannot be quickly exported. Gradually accumulate, which has a greater impact on the reliability of the phosphor. Most of the heat of the flip-chip chip is quickly introduced into the silicon substrate (thermal conductivity about 120W/mK) through the gold bump, and then introduced into the bracket by the silicon substrate, and the sapphire has a low thermal conductivity, only a small portion. The heat accumulates in the sapphire, achieving heat (downward emission) and light separation (upward injection) design, while the surface temperature of the sapphire is low, which can prolong the aging cycle of the phosphor and greatly improve the reliability and life of the LED. At the same time, due to the good thermal design of the flip-chip structure, the flip-chip 1W chip can have a better LI linear relationship (see Figure 3) and saturation current tolerance and high current withstand capability. The flip-chip 1W power chip can support long-term room temperature 780mA high current aging.

1W power chip installed street light example to analyze lighting effects

LED flip chip is gradually used by most domestic lighting manufacturers in street lighting with its low voltage (below 3.0V), high luminous efficiency (100-110lm/W) and high stability. A high-pressure sodium lamp and an LED street lamp are comparatively analyzed with a street lamp installed by a customer using a flip chip as an example. Before the renovation, Gangqian Avenue uses 400W (top light) + 150W (waist light) high-pressure sodium lamp street light. The daily power consumption per pole is 6.6 degrees. After renovation, 180W (top light) + 60W (waist light) LED street light is used. The power consumption is 3.1 degrees, the road lighting quality fully meets the requirements of the urban road lighting standard CJJ-45-2006, and the energy saving is 53%. The German LM-1009 road special narrow-angle brightness meter is used, according to the road illumination brightness measurement method (the measuring instrument is located 60 meters away from the initial measured point, the instrument height is 1.2 meters, measuring the highest and lowest brightness between the two poles along the centerline of the lane, measured point by point), the maximum illumination of the road before the transformation is 42Lx, the minimum illumination is 8Lx, the average The illuminance is 30Lx and the uniformity is 0.3. After the transformation, the maximum illumination of the road surface is 23Lx, the minimum illumination is 12Lx, the average illumination is 18Lx, and the uniformity is 0.75.

Since the color rendering of the LED light source is above 70, the brightness distribution is uniform, and the discrimination ability for the target is much better than that of the high-pressure sodium lamp with a color rendering index of 23. Under the condition of road illumination (intermediate vision), the illumination requirement of the white LED is appropriately reduced. (Reduced by 1/3), the same lighting effect as high pressure sodium lamps can be achieved. After the replacement of LED street lights in Gangqian Avenue, the overall uniformity, longitudinal uniformity and lateral uniformity of the road surface reached 0.70 or more, achieving good lighting effects.

Future LED chip development direction

At present, high-power LED street lamps are mainly realized by means of "multiple chips in series and parallel connection" and "multiple LEDs are connected in series through PCB". The former has not been widely used because of the need to match the photoelectric parameters between the chips, and the process unreliability and low package yield of multiple gold wire series and parallel packages. The latter requires strict photoelectric parameter matching for multiple LEDs, and optical design is difficult. Therefore, "chip-level" modular products are an important development direction for future LED chips. The chip-level LED module realizes the serial-parallel connection between the single chips through the circuit in the substrate, solves the problem that the traditional module integration relies on the gold wire for serial-parallel connection, greatly improves the product yield rate, and greatly reduces the production of the entire packaging process. Cost, strictly control the parameter difference between the chips of the integrated module chip to ensure the reliability of the long-term use of the module chip, and the module chip can be used as a unit to perform series-parallel splicing to form a module with higher power. With flip-chip technology, multi-chip integration of different sizes, colors, shapes, and powers can be realized at the "chip level" to realize ultra-high power module products, which is an advantage that cannot be achieved by any other chip technology.

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High Frequency PCB - Definition, Characteristics, Manufacturing, Materials and Application Scenarios

With the development of science and economy, the electronic industry has become an important driving force for economic development. Electronic products have become a part of life, affecting people's way of life. High-frequency circuit boards are widely used in many electronic industries and some instruments and equipment, and high-frequency PCB applications are also increasing. Choose high-frequency circuit board manufacturers in good service to buy high-quality products for use, we have to understand the relevant knowledge of high-frequency board.

High Frequency PCB

What Is A High Frequency Circuit Board?

High frequency circuit board (HF PCB) is a special circuit board with high electromagnetic frequency. Generally speaking, high frequencies can be defined as frequencies above 1GHz. Its physical performance, accuracy and technical parameters are very demanding. It is often used in automobile anti-collision system, satellite system, radio system and other fields.

High Frequency PCB include: 

  • Rogers high frequency PCB
  • Power amplifier high frequency PCB
  • Buried blind hole mixed high frequency PCB
  • Ceramic high frequency PCB
  • Ceramic mixed high frequency PCB
  • Communication antenna high frequency PCB
  • GPS antenna high frequency PCB
  • FR-4 high frequency PCB
  • Double sided high frequency PCB
  • Microwave High Frequency PCB
  • Induction High Frequency PCB
  • 2.4G Radar Induction PCB
  • 5.8G Microwave Induction PCB

High Frequency Circuit

A Practical New Patent Technology for High Frequency PCB

The utility model patented high frequency circuit board includes a core board with a hollow groove and a copper clad plate adhering to the surface and the lower surface of the core board by flow glue. The upper opening and the lower opening edges of the hollow groove are provided with a baffle.

The high frequency circuit board provided by the utility model is provided with a barrier which can block the flow glue at the upper and lower edges of the hollow groove of the core board.

In this way, the flow glue will not enter the hollow slot when the core plate is bonded with the copper clad laminate placed on the upper and lower surfaces, that is, the bonding operation can be completed by one press.

Compared with the existing technology, the high frequency circuit board can only be completed by secondary pressing. The high frequency circuit board in the utility model has the advantages of simple structure, low cost and easy manufacture.

Characteristics of High Frequency Circuit Board

Generally speaking, high frequency circuit boards have their own characteristics: low dielectric constant, relatively stable. In theory, the smaller the dielectric constant, the more stable the signal, and the higher the frequency circuit board can play a better role in signal transmission. Medium loss is very small, it is not easy to absorb water and moisture, heat resistance, corrosion resistance and other excellent performance. Conversely, if the dielectric constant is high, the signal transmission process is slow.
The thermal expansion coefficients of high frequency circuit boards and copper foil are also correlated to a certain extent. They are consistent as far as possible. The inconsistency can easily lead to the separation of copper foil in the alternate change of heat and cold. The later use will affect the signal transmission of PCB. The absorbency of high frequency circuit board is lower than that of other multi-layer circuit boards, because humidity will affect the dielectric constant and dielectric loss of high frequency circuit board. In addition, the heat resistance, chemical resistance, impact strength, peeling strength and other requirements are also good.

High frequency signals are vulnerable to noise and come with much tighter impedance tolerance as compared to conventional circuit boards.

High Frequency PCB

High Frequency Circuit Board Materials

High frequency PCB have their own unique plates. Special materials are used to attain the high frequency given by the High Frequency PCB. PCB manufacturer commonly used Materials are: rogers(Rogers 4350B HF.Rogers RO3001.Rogers RO3003).Taconic(RF-35 Ceramic.TLX). Arlon(85N).Isola(IS620 E-fibre glass).F4B.TP-2.FR-4,Dielectric constant 2.2-10.6 and so on. FR4 is the cheapest one, while Teflon is the most expensive one. But they all have a common characteristic, which is the resin used in the material. The wiring of high frequency circuit board is exquisite and has great influence on components. High-frequency signals have the strongest impact on analog devices, so we should deal with the relationship between them to achieve the best performance. Therefore, high frequency is not easy to pass through high capacity electrolytic capacitors with poor high frequency performance.

The substrate material used in the high-frequency circuit board needs to have excellent electrical properties, good chemical stability, and the loss on the substrate is very small as the frequency of the power signal increases, so the importance of the high-frequency board is highlighted.

Therefore, when selecting a substrate for a PCB for a high-frequency circuit, it is particularly necessary to examine the various characteristics of the material DK at different frequencies. For the requirements of high-speed transmission of signal emphasis, or characteristic impedance control requirements, focus on DF and its performance under conditions of frequency, temperature and humidity.

Under the condition of frequency change, the general type of substrate material shows a large change of DK and DF values. Especially in the frequency range of l MHz to l GHz, their DK and DF values change more significantly. For example, a general-type epoxy resin-glass fiber-based substrate material (general type FR-4) has a DK value of 4.7 at a frequency of 1 MHz, and a DK value of 4.19 at a frequency of 1 GHz. Above lGHz, its DK value tends to be flat. The changing trend is smaller as the frequency increases (but the change is not large). For example, at 10 GHz, the DK value of FR-4 is generally 4.15, and the substrate material having high-speed and high-frequency characteristics changes in frequency. In the case of DK, the DK value changes little, and the DK keeps changing in the range of 0.02 from the frequency of change from 1 MHz to 1 GHz. Its DK value tends to decrease slightly from low to high frequency.

The dielectric loss factor (DF) of a general type of substrate material is affected by a change in frequency (especially in a high-frequency range), and the change in DF value is larger than that of DK. The law of change tends to increase. Therefore, when evaluating the high-frequency characteristics of substrate material, the focus of its investigation is on the change of its DF value. There are two distinct types of two types of substrate materials with high-speed and high-frequency characteristics. In general, there are two different types of substrate materials: one is that the (DF) value changes little with frequency. There is also a class that, although similar in magnitude to the general substrate material, has a lower (DF) value.

High-frequency circuit boards with induction heating technology have been widely used in the communication industry, network technology field promotion and high-speed information processing systems to meet the requirements of many high-precision parameter instruments. A reliable high-frequency circuit board provides great help in actual production.

From material DF:

The circuit board material with DF between 0.01 and 0.005 is suitable for the digital circuit with the upper limit of 10Gb / S;

DF between 0.005-0.003 is suitable for digital circuits with an upper limit of 25gb / s;

Circuit board materials with DF no more than 0.0015 are suitable for 50GB / s or even higher speed digital circuits.

Common high-speed PCB materials are:

1) Rogers: ro4003, ro3003, ro4350, ro5880, etc

2) TUC: tuc862, 872slk, 883, 933, etc

3) Panasonic:Megtron4.Megtron6, etc

4) Isola: fr408hr, is620, is680, etc

5) Nelco:N4000-13.N4000-13EPSI, etc

6) ShengYi

Of course, there are many other high-frequency board materials, such as Arlon (acquired by Rogers) and Taconic, which are all old brand RF microwave material factories with guaranteed performance.

Our most common request is for FR-4 material, which is composed of woven fiberglass bound by an epoxy resin, and which we always keep stocked as one of our PCB Options at a Standard Price. FR-4 is a robust material with excellent thermal characteristics, and electrically it is known to perform quite reasonably at RF or Microwave frequency levels. 

Some clients whose designs are intended for particularly demanding applications-such as high-power or broadband circuits-find that FR-4 sometimes just does not do the job at those higher frequencies. In these cases, we are always happy to help you find a laminate material to suit your specific needs, and our highly customizable PCB Assembly Process can be easily adjusted to make sure your project lead time is not impacted.

A snapshot of the datasheet for FR-4 material is shown below for reference. 

High Frequency PCB Materials-FR4

The most popular high-frequency-specific laminate materials were developed by Rogers, and referred to with an [RO-[ prefix. These high-quality materials exhibit approximately a 20% reduction in dielectric constant, compared to standard FR-4; they also boast rather impressive thermal characteristics, with Tg values above 280°C . A snapshot of the datasheet for RO4350B and RO4003C is included below for your convenience. 

High Frequency PCB Materials-Rogers

Requirements for Manufacturing Materials of High Frequency PCB

1. Dielectric loss (Df) must be small, which mainly affects the quality of signal transmission. The smaller the dielectric loss, the smaller the signal loss.

2. Low water absorption. High water absorption will affect dielectric constant and dielectric loss when damped.

3. The dielectric constant (DK) must be small and stable. Usually the smaller the better. The transmission rate of the signal is inversely proportional to the square root of the dielectric constant of the material. High dielectric constant easily causes signal transmission delay.

4. The coefficient of thermal expansion of copper foil is the same as that of copper foil, because the inconsistency will cause the separation of copper foil in the change of cold and heat.

5. Other heat resistance, chemical resistance, impact strength and peeling strength must also be good.

Generally speaking, high frequency can be defined as frequency above 1 GHz. At present, most of the high frequencies used are fluorine dielectric substrates. Teflon is much better than other substrates, such as PTFE, which is usually called Teflon.  However, Teflon substrate has the disadvantage of high cost and large heat resisting property.

How to choose high frequency high speed PCB material

To select the PCB substrate, a balance must be made among meeting the design requirements, mass production and cost. In short, the design requirements include electrical and structural reliability. Generally, when designing a very high-speed PCB Board (frequency greater than GHz), PCB material problem will be more important. For example, the FR-4 material, which is commonly used now, has a large dielectric loss DF (dielectric loss) at several GHz, which may not be applicable.

For example, 10Gb / s high-speed digital signal is a square wave, which can be regarded as the superposition of sine wave signals of different frequencies. Therefore, 10Gb / s contains many different frequency signals: 5GHz fundamental signal, 3-order 15GHz, 5-order 25ghz, 7-order 35GHz signal, etc. The integrity of the digital signal and the steepness of the upper and lower edge are the same as the low loss and low distortion transmission of the RF microwave (the high-frequency harmonic part of the digital signal reaches the microwave frequency band). Therefore, in many aspects, the selection of high-speed digital circuit materials is similar to the requirements of RF microwave circuits.

The main factors to be considered in the selection of suitable base materials are as follows:

1. Manufacturability:

2. Various performances (electrical, performance stability, etc.) matching with products:

Low loss, stable Dk/Df parameters, low dispersion, small variation coefficient with frequency and environment, small tolerance of material thickness and glue content (good impedance control), if the trace is long, consider low roughness copper foil. In addition, the high-speed circuit needs to be simulated in the early stage of design, and the simulation result is the reference standard of the design. "Xingsen Technology-Agilent (High Speed/RF) Joint Lab" solves the performance problems of inconsistent simulation results and tests. It has done a lot of simulation and actual test closed-loop verification, and the simulation can be consistent with the actual measurement through unique methods.

3. The availability of materials in a timely manner:

Many high-frequency board material procurement cycles are very long, even 2-3 months; in addition to the conventional high-frequency board material RO4350 in stock, many high-frequency boards material need to be provided by customers. Therefore, high-frequency plates need to communicate with manufacturers in advance, and prepare materials as soon as possible;

4. Cost:

5. Applicability of laws and regulations:

It should be integrated with environmental protection regulations of different countries to meet the requirements of RoHS and halogen-free.

Among the above factors, the high-speed digital circuit operation speed is the main factor to be considered in PCB material selection. The higher the speed of the circuit, the smaller the DF value of the selected PCB material. The low loss circuit board will be suitable for 10Gb / s digital circuit; 25gb / s digital circuit needs to select the board with lower loss; ultra-low loss board will be suitable for the faster high-speed digital circuits, and its speed can be 50GB / s or higher.

How to Make High Frequency Circuit Board?

High Frequency PCB

Fabrication Principle of High Frequency Circuit Board

In the design of high frequency circuit, the power supply is designed in the form of layers, which is much better than that in the form of buses in most cases, so that the circuit can always follow the path with the smallest impedance. In addition, the power board has to provide a signal loop for all generated and received signals on PCB, which can minimize the signal loop and reduce noise, which is often ignored by low frequency circuit designers.

In the design of high frequency PCB, we should follow the following principles:

  • Unity of power supply and ground, stability.

  • Careful wiring and proper termination can eliminate reflection.

  • Careful consideration of wiring and proper termination can reduce capacitive and inductive crosstalk.

  • Noise suppression is needed to meet EMC requirements.

Points for Attention in Manufacturing High Frequency Circuit Board

1. Impedance control is strict, relative line width control is very strict, general tolerance is about 2%.

2. Because of the special plate, the adhesion of PTH copper deposit is not high. Usually, plasma treatment equipment is needed to roughen the through-hole and surface to increase the adhesion of PTH copper and solder resist ink.

3. Do not grind the plate before welding resistance, otherwise the adhesion will be very poor, and can only be coarsened with micro-corrosive powder.

4. Most of the sheets are PTFE materials. There will be many rough edges when they are formed by ordinary milling cutters, which need special milling cutters.

5. High frequency circuit board is a special circuit board with high electromagnetic frequency. Generally speaking, high frequency can be defined as frequency above 1 GHz.

Its physical performance, accuracy and technical parameters are very demanding. It is often used in automobile anti-collision system, satellite system, radio system and other fields.

Scenario and Field of High Frequency Circuit Board Application:

  • Communication Base Station
  • Repeater
  • GPS antenna
  • Radio Frequency Antenna
  • power amplifier
  • Signal amplifier
  • Wave filter
  • coupler
  • attenuator
  • Power divider
  • 3DB Bridge, etc.
Nowadays, the high frequency of electronic equipment has become a trend of development, especially in the growing development of communication networks, aerospace, military equipment, intelligent transportation, information products are also increasingly high-speed and high-frequency. Nowadays, with the development of science and economy, many new products need high frequency circuit boards. High frequency circuit boards play an increasingly important role in people's daily life.

It is not easy to find a fast and good manufacturer of high frequency circuit boards. Jinghongyi PCB has its own unique board advantages in making high frequency circuit boards. It has reliable automatic production equipment and testing equipment.

Reasons for Choosing Jinghongyi PCB

1. Top imported raw materials for high frequency circuit boards to ensure product quality from the source

  • Plate: Shengyi, South Asia, KB.Rogers.Taconic. Isola. Arlon.F4BM.Nelco.Hitachi.
  • Potions: Rohm&Haas (US) Atotech (Germany) Umicore (Germany)
  • Ink: Taiyo (Japan) 
  • Dry membrane: Asahi (Japan), Dupont (US)

2. Full set of surface treatment equipment to meet the needs of various industries

We are one of the few companies in PCB industry equipped with complete surface treatment equipment.We can deal with the Immersion Gold completely.

Immersion Silver, Immersion tin, OSP, tin spraying, gold plating, thick gold plating, tin plating, silver plating and other related requirements.

3. Leading PCB Multilayer Circuit Board Technology Capability

  • Maximum Layer: 28 layer
  • Maximum Plate Thickness: 6.0mm
  • Maximum Thickness to Diameter Ratio 10:1
  • Maximum Copper Thickness: 6OZ
  • Maximum working plate size: 1000x610mm
  • Thinnest 4 Layer PCB : 0.33mm
  • Minimum mechanical hole/pad: 0.2/0.40mm
  • Drilling accuracy: +/-0.05mm
  • PTH Aperture Tolerance: +/-0.05mm
  • Minimum Linewidth/Line Spacing: 3mil/0.075mm

4. Strict PCB quality control system to effectively guarantee product performance

  • Strictly control according to IPC standard to ensure 100% qualified rate of shipment quality.

  • Implement quality PDCA cycle process to continuously improve product performance

  • Imported DIONEXICS-900 and Temperature Cycle Inspection Equipment from USA to ensure high reliability and stability of products

5. Top Technical Team

Eight years of focus on R&D and manufacture of high-frequency board and microwave radar RF circuit board, with a dedicated, united and tenacious R&D team, customers NPI stage products, all into the process evaluation system, meet the evaluation criteria of the project, further review by the R&D team and file a case tracking the whole process.

The staff has 3-12 years of professional and technical personnel with multi-layer circuit board experience. They have rich experience in various industry standards and process quality requirements.

6. Intimate service

Service concept: regard customers as eternal partners, develop together, only choose reputation, not customers, regardless of the size of customers, in the case of customer needs, to provide the best service.

Flexible service: We will be eager to meet the customers'needs, think what they want, and do our best to help customers solve problems, reduce losses or promote project development.

Useful Resources

High Frequency PCB

High Frequency PCB, High Frequency Circuit Board, High Frequency PCB Design, High Frequency PCB Materials

JingHongYi PCB (HK) Co., Limited , https://www.pcbjhy.com

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