PCB Raw Material Cost Go Up Crazy

PCB raw materials will continue to increase in price in 2021

PCB raw materials include copper foil, fiberglass, resin and other related materials have been reported of price adjustments in Q1 of 2021.Recently, from CCL factory to PCB factory, we have received notices about product price increase.Even PCB industry has fired the first shot, pointing out that the purchased high-end CCL materials have officially increased in price. The relevant supply chain industry confessed that the supply of PCB upstream materials will be very tight throughout 2021 under the unbalanced growth of supply and demand, and there will only be more and more cases of price increases.

Copper prices have soared in the past two months, and will exceed the $8,000 mark per metric ton at any time. The high-end reversal copper foil required for high-frequency and high-speed materials has caused various PCB and IC substrate manufacturers to raise prices and grab production capacity due to the scarcity and small scale of suppliers. In addition, there has been a surge in demand for electrolytic copper foil for electric vehicle batteries in the past, The supply of rolled copper foil required for extrusion to PCB may happen again in 2021.

In terms of fiberglass, only a few Japanese chemical material companies such as Nitto Boseki can supply. There was a fire in Nittobo in 2020, and the market demand may rise further in 2021, and the PCB supply chain may have to raise prices to grab goods.

The resin part has a similar situation, the same is that the expansion speed of high-end products cannot keep up with demand.At the same time, an accident happened to impact the operation of the production line.

On the whole, regardless of price changes, the tightness of upstream PCB materials is inevitable condition.

Chemical raw materials have always been the strengths of large Japanese factories, and many PCB raw materials are still imported from Japanese original factories, especially High-end materials. The relevant supply chain revealed that most Japanese chemical material companies are controlled by large consortia, and they often have to consider operating strategies and tend to be conservative when expanding production capacity. The adjustment flexibility is also relatively low, and the spread of the epidemic in Japan is likely to be more serious than the official announcement. The stability of the supply of Japanese chemical materials is also a big risk.

PCB manufacturers are unable to withstand the upward pressure of price increases from the raw material manufacturers. In order to ensure stable supply, they have to accept the cost transfer of the CCL factory and have no choice but to pass the cost to customers.

In addition, different applications and end customers will also determine the actual impact of price increases. For example, IC substrates that have recently increased by another wave usually face adjustments in upstream material prices. The entire upstream and downstream all the way to the end customers to discuss the cost transfer situation, as far as possible to reduce the damage of all levels of manufacturers from the price increase to the lowest.

Posted on 23 Feb 2021
By info@kingsunpcb.com
In PCB knowledge

High Frequency Circuit Board Design Interference Solution

In the design of the circuit board, with the rapid increase of frequency, there will be many interferences different from the design of the low frequency PCB. As the frequency increases and the contradiction between the miniaturization and cost reduction of PCB boards becomes more and more prominent, these interferences are more and more complicated. In the actual research, we conclude that there are four main types of interference, including power supply noise, transmission line interference, coupling, and electromagnetic interference (EMI). By analyzing various interference problems of high-frequency PCBs, combined with practice in practice, an effective solution is proposed.

Power supply noise

In high-frequency circuits, the noise of the power supply is particularly significant for high-frequency signals. Therefore, the power supply is first required to be low noise. Here, clean ground and clean power are just as important, why? The power supply characteristics are shown in Figure 1. Obviously, the power supply has a certain impedance, and the impedance is distributed over the entire power supply, so the noise is also superimposed on the power supply. Then we should reduce the impedance of the power supply as much as possible, so it is best to have a proprietary power plane and ground plane. In high-frequency circuit design, the power supply is designed in layers, which is much better in most cases than in the form of a bus, so that the loop can always follow the path with the least impedance.In addition, the power board has to provide a signal loop for all generated and received signals on the PCB, which minimizes the signal loop and reduces noise, which is often overlooked by low-frequency circuit designers.

There are several ways to eliminate power supply noise in PCB design:

Pay attention to the through hole on the board

The through holes make it necessary to etch the openings on the power supply layer to allow space for the through holes to pass. If the power supply layer is too large, it will affect the signal loop, the signal will be forced to bypass, the loop area will increase, and the noise will increase. At the same time, if some signal lines are concentrated near the opening, sharing this loop, the common impedance will cause crosstalk.

The cable needs enough ground wire

Each signal needs its own proprietary signal loop, and the loop area of the signal and loop is as small as possible, that is, the signal is parallel to the loop.

Analog and digital power supply should be separated

High-frequency devices are generally very sensitive to digital noise, so the two should be separated and connected together at the entrance of the power supply. If the signal crosses both analog and digital, a loop can be placed at the signal crossing to reduce the loop area.

Avoid separate power supplies that overlap between different layers

otherwise circuit noise is easily coupled through parasitic capacitance.

Place the power cord

To reduce the signal loop, reduce the noise by placing the power line on the side of the signal line.

Transmission line

Only two transmission lines are possible in the PCB: stripline and microwave.

The biggest problem with transmission lines is reflection. Reflections cause many problems. For example, the load signal will be the superposition of the original signal and the echo signal, which will increase the difficulty of signal analysis. The reflection will cause return loss (return loss), which is generated by the signal. The impact is equally severe with the effects of additive noise interference:

Signal reflection back to the signal source will increase system noise, making it more difficult for the receiver to distinguish noise from signal.
Any reflected signal will basically reduce the signal quality, which will change the shape of the input signal.

In principle, the solution is mainly impedance matching (for example, the interconnection impedance should match the impedance of the system). However, sometimes the calculation of the impedance is troublesome. You can refer to some calculation software for transmission line impedance. The method to eliminate transmission line interference in PCB design is as follows:

(a) Avoid impedance discontinuities in the transmission line.

The point at which the impedance is discontinuous is the point at which the transmission line is abrupt, such as a straight corner, a via, etc., and should be avoided as much as possible. The method is as follows: avoid straight corners of the traces, as far as possible to take a 45° angle or an arc, and a large corner can also be used; use vias as little as possible because each via is a discontinuous point of impedance; the outer layer signal is avoided The inner layer and vice versa.

(b) Do not use pile lines.

Because any pile line is a source of noise. If the pile line is short, it can be terminated at the end of the transmission line; if the pile line is long, the main transmission line will be the source, which will cause a large reflection, which complicates the problem and is not recommended.

Coupling

Common impedance coupling

It is a common coupling channel, that is, the interference source and the interfered device often share certain conductors (such as loop power, bus, common ground, etc.), as shown in Figure 6. On this channel, the falling back of Ic causes a common mode voltage in the series current loop, affecting the receiver.

Field common mode coupling will cause the radiation source to cause a common mode voltage on the loop formed by the disturbed circuit and the common reference plane.

If the magnetic field is dominant, the value of the common mode voltage generated in the series-connected loop is Vcm=-(ΔB/Δt)* area (where ΔB=the amount of change in the magnetic induction). If it is an electromagnetic field, it is known. Its electric field value, its induced voltage: Vcm = (L * h * F * E) / 48, the formula is suitable for L (m) = 150MHz or less, beyond this limit, the calculation of the maximum induced voltage can be simplified as: Vcm = 2*h*E.

Differential mode field coupling

Refers to the direct radiation being sensed by the wire pair or the leads on the board and its loop. If possible as close as possible to the two wires. This coupling is greatly reduced, so the two wires can be twisted together to reduce interference.

Inter-line coupling

Line-to-line coupling (crosstalk) can cause any line to be equal to unwanted coupling between parallel circuits, which can severely compromise system performance. The types can be classified into capacitive crosstalk and inductive crosstalk.

The former is because the parasitic capacitance between the lines causes the noise on the noise source to be coupled to the noise receiving line by the injection of current; the latter can be thought of as the coupling of the signal between an undesired primary and secondary of the parasitic transformer. The magnitude of the inductive crosstalk depends on the proximity of the two loops and the size of the loop area, as well as the impedance of the affected load.

Power line coupling

When the AC or DC power line is subjected to electromagnetic interference, the power line transmits these interferences to other devices.

Method for eliminating crosstalk in PCB design

The magnitude of both crosstalk increases as the load impedance increases, so the signal lines sensitive to interference caused by crosstalk should be properly terminated.
Increase the distance between signal lines as much as possible, which can effectively reduce capacitive crosstalk. Ground layer management is performed, and the spacing between the wirings is made (for example, the active signal lines and the ground lines are isolated, especially between the signal lines where the state jumps and the ground), and the lead inductance is reduced.
Inserting a ground line between adjacent signal lines can also effectively reduce capacitive crosstalk, which requires access to the ground plane every 1/4 wavelength.
For inductive crosstalk, minimize the loop area and, if possible, eliminate this loop.
Avoid signal sharing loops.
Focus on signal integrity: The designer must implement termination during the soldering process to resolve signal integrity. Designers using this approach can focus on shielding the microstrip length of the copper foil for good signal integrity. For systems that use dense connectors in the communication structure, the designer can terminate with a single PCB.
Electromagnetic interference

As speed increases, EMI will become more severe and manifest itself in many ways (such as electromagnetic interference at the interconnect), which is especially sensitive to high-speed devices, which will therefore receive high-speed spurious signals at low speeds. The device will ignore such false signals.

There are several ways to eliminate electromagnetic interference in PCB design:

Reduce the loop

Each loop is equivalent to an antenna, so we need to minimize the number of loops, the area of the loop, and the antenna effect of the loop. Make sure that the signal has only one loop path at any two points, avoiding artificial loops and using the power plane as much as possible.

Filtering

Filtering can be used on the power line and on the signal line to reduce EMI. There are three methods: decoupling capacitors, EMI filters, and magnetic components.

Minimize the speed of high frequency devices

Increase the dielectric constant of the PCB board / Increase the thickness of the PCB board

Increasing the dielectric constant of the PCB board can prevent the high-frequency part of the transmission line close to the board from radiating outward; increasing the thickness of the PCB board and minimizing the thickness of the microstrip line can prevent the overflow of the electromagnetic line and also prevent radiation.

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

The power and the ground are unified and stable.
Careful wiring and proper termination can eliminate reflections.
Careful wiring and proper termination can reduce capacitive and inductive crosstalk.
Need to suppress noise to meet EMC requirements.

Posted on 17 Oct 2019
By info@kingsunpcb.com
In PCB knowledge

Why use ceramics materials for PCB boards?

Ceramic circuit boards are actually made of electronic ceramic materials and can be made into various shapes.Among them, the ceramic circuit board has the characteristics of high temperature resistance and high electrical insulation performance, and has the advantages of low dielectric constant, low dielectric loss, high thermal conductivity, good chemical stability, and similar thermal expansion coefficients of components. Ceramic printed circuit boards are produced using laser rapid activation metallization technology LAM technology. Used in LED field, high power semiconductor modules, semiconductor coolers, electronic heaters, power control circuits, power mixing circuits, smart power components, high frequency switching power supplies, solid state relays, automotive electronics, communications, aerospace and military electronic components.

Unlike traditional FR-4 (glass fiber), ceramic materials have good high frequency performance and electrical properties, and have high thermal conductivity, chemical stability and thermal stability. Ideal packaging material for generating large scale integrated circuits and power electronics modules.
Main advantages:
1, the thermal conductivity is higher
2, a more matching coefficient of thermal expansion
3. A harder, lower resistance metal film alumina ceramic circuit board
4. The solderability of the substrate is good and the use temperature is high.
5, good insulation
6, low frequency loss
7, assembled at high density
8, free of organic components, resistant to cosmic rays, high aerospace reliability, long service life
9. The copper layer does not contain an oxide layer and can be used for a long time in a reducing atmosphere.

With the development of high-power electronic products in the direction of miniaturization and high speed, traditional FR-4, aluminum substrate and other substrate materials are no longer suitable for the development of high power and high power. With the advancement of science and technology, the intelligent application of the PCB industry. Traditional LTCC and DBC technologies are gradually being replaced by DPC and LAM technologies. Laser technology, represented by LAM technology, is more in line with the development of high-density interconnects and fineness of printed circuit boards. Laser drilling is the front end of the PCB industry and mainstream drilling technology. The technology is efficient, fast, accurate and has high application value. The RayMingceramic board is made with laser fast activation metallization technology. The bonding strength between the metal layer and the ceramic is high, the electrical properties are good, and the soldering can be repeated. The thickness of the metal layer can be adjusted in the range of 1 μm to 1 mm, and L/S resolution can be achieved. 20μm, which can be directly connected to provide customized solutions for customers.

Lateral Excitation of Atmospheric CO2 Laser This product was developed by a Canadian company and has an output power of one hundred to one thousand times compared to conventional lasers and is easy to manufacture. In the electromagnetic spectrum, the radio frequency is in the frequency range of 105-109 Hz, and with the development of military and aerospace technology, the second frequency is transmitted. The medium and small power RF CO2 lasers have excellent modulation performance, stable power and high operational reliability. Long life and other characteristics. UV solid YAG is widely used in plastics and metals in the microelectronics industry. Although the CO2 laser drilling process is more complicated, the production effect of micro-aperture is better than that of UV solid YAG, but CO2 laser has the advantages of high efficiency and high-speed stamping. The market share of PCB laser micro-hole processing can still be developed in domestic laser micro-hole manufacturing. At the stage, not many companies can put into production.

Domestic laser micro-hole manufacturing is still in the development stage. Short pulse and high peak power lasers are used to drill holes in the PCB substrate to achieve high density energy, material removal and micropore formation. Ablation is divided into photothermal ablation and photochemical ablation. Photothermal ablation refers to the process of forming pores by rapidly absorbing high-energy laser light through the substrate material. Photochemical ablation refers to a combination of high photon energy in the ultraviolet region of more than 2 eV electron volts and laser wavelengths in excess of 400 nm. The manufacturing process can effectively destroy the long molecular chain of the organic material, form smaller particles, and the particles can rapidly form micropores under the action of external force.

Today, China’s laser drilling technology has certain experience and technological progress. Compared with traditional stamping technology, laser drilling technology has high precision, high speed, high efficiency, large-scale batch punching, suitable for most soft and hard materials, without loss of tools and waste. The advantages of less material, environmental protection and no pollution.

The ceramic circuit board passes the laser drilling process, the bonding force between ceramic and metal is high, does not fall off, foaming, etc., and the effect of growth together, high surface flatness, roughness ratio of 0.1 micron to 0.3 micron, laser striking hole diameter From 0.15 mm to 0.5 mm, even 0.06 mm.

Posted on 9 Oct 2019
By info@kingsunpcb.com
In PCB knowledge

What are the materials of the PCB board?

PCB materials types included HB sheet and V0 sheet

HB sheet has low flame retardancy and is mostly used for single-layer PCB. VO sheet has high flame retardancy. It is mostly used in double-sides and multi-layer boards. This type of PCB sheet meets V-1 fire rating requirements and becomes FR-4 sheet. V-0, V-1, V-2 are fire rated.

The flammability of the material, also known as flame retardancy, self-extinguishing flame resistance, flame retardancy, fire resistance, flammability, etc., is a measure of the resistance of the material to resistance to combustion.

The flammable material sample is ignited by the required flame, the flame is removed after the specified time, and the flammability grade is evaluated according to the degree of combustion of the sample. The flammability grade is divided into three levels, and the sample is horizontally placed into a horizontal test method, which is divided into FH1, FH2. , FH3 three-stage, the sample is placed vertically for vertical test method is divided into FV0, FV1, VF2.

The circuit board must be flame resistant, cannot burn at a certain temperature, and can only soften. The temperature point at this time is called the glass transition temperature (Tg point), which is related to the dimensional stability of the PCB.

What types of PCB boards are there?

According to the grade level, from bottom to top are divided as follows:94HB – 94VO – 22F – CEM-1 – CEM-3 – FR-4 is described in detail as follows:

94HB: ordinary cardboard, not fireproof (minimum material, die punching, can not be used as power board)
94V0: flame retardant cardboard (mode Punching)
22F: single-sided semi-glass fiberboard (die punching)
CEM-1: single-sided fiberglass board (must be drilled by computer, can not be punched)
CEM-3: double-sided semi-fiberglass board (except double-sided The outermost part of the double-panel material is made of cardboard. The simple double-panel can use this material, which is a little bit cheaper than FR-4.
FR-4: double-sided fiberglass board

What is high Tg PCB?

High Tg refers to high heat resistance. With the rapid development of the electronics industry, especially the electronic products represented by computers, the development of high functionality and high multi-layer requires the higher heat resistance of PCB substrate materials as an important guarantee. The emergence and development of high-density mounting technology represented by SMT and CMT makes PCBs more and more inseparable from the high heat resistance of substrates in terms of small aperture, fine wiring and thinning.
Generally, Tg degrees are above 130 degrees, high Tg is generally greater than 170 degrees, and medium Tg is greater than about 150 degrees. A PCB printed board with a typical Tg ≥ 170 ° C is called a high Tg printed board. The Tg of the substrate is improved, and the heat resistance, moisture resistance, chemical resistance, and stability resistance of the printed board are improved. The higher the TG value, the better the temperature resistance of the sheet, especially in the lead-free process, where high Tg is applied.

What are the advantages of high Tg PCB boards and the use of high Tg PCBs?

High Tg printed board When the temperature rises to a certain area, the substrate will change from “glass state” to “rubber state”, and the temperature at this time is called the glass transition temperature (Tg) of the plate. In other words, Tg is the highest temperature at which the substrate remains rigid.

So the difference between the general FR-4 and the high Tg FR-4:

It’s in the hot state, especially after moisture absorption.Under heat, there are differences in mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition, and thermal expansion of materials. High Tg products are obviously better than ordinary PCB substrate materials. In recent years, customers demanding the production of high Tg printed boards have increased year by year.

Posted on 8 Oct 2019
By info@kingsunpcb.com
In PCB knowledge

The Difference Between PCB ENIG and PCB Gold Plating

In the early PCB manufacture, HASL is the most widely used surface treatment, which has excellent welding performance and low cost.With the high precision PCBs developing, it is difficult to below the surface to smooth of HASL, which brings difficulties to SMT mounting. In addition, the service life of HASL board is very short, and the ENIG PCBs and gold plating PCB just solved the problems.

ENIG PCBs and gold plating PCBs have many advantages over HASL PCB.

The surface is smooth.
Good solderability, good heat dissipation, gold wire bonding can be made
Long storage time. (Vacuum packaging can be kept for more than one year)
Resistant reflow welding and can be reworked many times.

Speaking of gold plating, PCB factories will ask you whether you are making ENIG or gold plating, soft gold or hard gold. For PCB designers, they are confused. Today we will talk about different kinds of gold plating PCBs.

According to the different processing technology, it can be divided into electroplating gold(gold plating) and Immersion Gold (ENIG).

Electroplated gold is divided into soft gold and hard gold according to the purity of gold.

Soft gold: Pure gold is soft because of its high purity.

Hard gold: In order to increase the surface hardness, and increase other metals called hard gold.

Immersion Gold (ENIG):

Immersion Gold is a process of thin gold deposition by controlled redox reaction under the catalysis of metals.Chemical replacement method is used to produce the effect of surface gold layer, so the maximum thickness of the gold layer can not achieve the same thickness as electroplated gold in principle, and the lower the gold content, the thickness is generally 1-3 micro inches.

Immersion Gold(ENIG) process:

Whole hole – -> Degreasing – -> Washing – – >Erosion – -> Washing – -> Activation – -> Washing – – >Nickel Immerse – -> Washing – – > Gold Immerse – – >Washing – -> Drying.

Whole hole: Hydrochloric acid or thiourea is used to deactivate the remaining palladium in the non-conducting pore to prevent it from sinking nickel and gold.

Degreasing: Use acid degreasing agent to remove light grease and oxides from copper surface, so as to make copper surface clean and increase wettability.

Water washing: Back-flow water washing after oil cylinder removal.

Microetching: Sodium persulfate etching solution is used to coarsen the copper surface and increase the precision of copper and chemical nickel layers.

Activation: In the electrochemical sequence, copper is located behind nickel, so it is necessary to activate the copper surface before electroless nickel plating. PCB industry mostly uses the method of producing a layer of replacement palladium layer on the copper surface to activate it. Activators are generally sulfuric acid type and hydrochloric acid type. Now more palladium sulfate type is used to activate night, and the effect is ideal.

Nickel precipitation: Nickel ions are deposited on bare copper surface under the reduction condition of sodium hypophosphite under the activation of palladium. When nickel deposits are coated with Pd-catalyzed crystals, the autocatalytic reaction will continue until the required nickel layer thickness.

Gold Deposition: After nickel plating on PCB plate is put into the gold trough, the nickel surface is attacked by the trough solution and nickel ions are dissolved. The two electrons thrown out are obtained by gold cyanide ions and gold deposits on the nickel surface.

Immersion Gold PCB is superior to gold-plated PCB in the following aspects:

Immersion Gold is easier to weld than gold plating, and will not cause bad welding.
There is only nickel and gold on the pad, which has little effect on the signal transmission in the skin effect.
Immersion Gold deposits are more dense than gold plated crystals and are not easy to oxidize.
Immersion gold is only needed for the location of window opening, and the cost can also be well controlled.

Gold-plated PCB boards are often used in gold finger boards and bonding boards because of their excellent electrical conductivity, wear resistance and oxidation resistance.

The gold layer on PCB boards acts as a metal corrosion resistance layer, which can withstand all general etching solutions. It has a high conductivity. Because of its negative oxidation potential, it is a good metal for corrosion resistance.

Posted on 2 Jul 2019
By info@kingsunpcb.com
In Technology

Do You Know How Many Types Of PCB Holes Are?

Via, through hole, blind hole, buried hole, partial depth hole, countersink hole, back drilling and press-fit hole, is it very dizzy? I will take you to know all kinds of holes in PCB.

PCB via

PCB via is an important part of PCB. It is the electrical connection guide hole between different layers, joined the printed wiring between the layer and the layer together. It is made from the copper precipitation process. Drilling costs usually account for 30% to 40% of PCB board costs. Therefore, when drawing the PCB board, the vias diameter should be larger than 0.25mm, and the pad diameter should be larger than 0.4mm, otherwise the PCB manufacturing cost will be increased.

PCB through hole

PCB through holes(PTH) is the general name of electronic industry for through-hole plug-in components.The metal tube is connected with the top and bottom circuit of the double-sided board through the surface of the copper hole of the circuit board, and connecte the inner layer in multilayer PCB. PTH holes are relatively inexpensive because of their larger diameters. The disadvantage is that it takes up a lot of effective space. A large number of dense through-hole occupy the trace space and obstacles the layout of inner layer. They pass through the surface of the power supply and the ground layer, and also destroy the impedance characteristics of the power ground layer, causing the power ground wire layer to fail.

PCB blind via

The blind via connect PCB outer circuit and inner layer for electro connection, and it can not see the opposite layer through the via, so it is called blind via. In the PCB design, although the pad and via diameter has been gradually reduced, if the PCB thickness does not decrease proportionally, the aspect ratio of the through hole will increase. The aspect ratio of the through-hole will result in insufficient copper deposition in the hole, thereby reducing product reliability. With the maturity of advanced laser drilling technology and plasma dry etching technology, The blind holes and burial holes of small aperture have come into being. If these non conducting apertures are 0.3mm, the parasitic parameters are about 1/10 of the original conventional holes, and the reliability of PCB is improved. In the production of PCB, special attention should be paid to the depth of drilling (Z axis) to be right, otherwise it will cause electroplating difficulties in holes. Drill the hole in the individual circuit layer in advance before drilling the circuit, and finally press it again. More precise positioning and alignment devices are needed.

PCB buried via

The buried hole is connected to any circuit layer inside the PCB but not through to the outer layer. Due to the use of non through hole technology, large holes in the PCB are few, thus providing more space for the routing. The remaining space can be used for large area shielding to improve EMI/RFI performance. At the same time, more residual space can also be used for shielding the inner part of the device and the key network line, so that it has the best electrical performance. The use of non through holes can make the pin out of the device more convenient, making the high-density pin devices such as the BGA package easy to wire, shorten the length of the connection, and meet the timing requirements of the high-speed circuit. In the manufacturing process of PCB, blind hole is made by partical vias electroplating in the inner layer. Finally,press with the outer layer and re drilling,it is more complex than the through hole, and the increase of the laminates leads to the high price of the blind hole.

PCB hole partial depth drill

Partial depth drill is drilling without through the circuit board to control certain depth. There are many kinds of depth drilling hole. Generally, drill holes are controlled by mechanical drills to control the height of spindle drills. There are mechanical blind holes, back drills, etc., and some are controlled by depth milling. The mechanism is almost the same.

PCB countersink hole

The head part of the fastener or completely immersed in the hole of the PCB is called the countersink hole. The countersunk hole of the PCB board is mainly used to make all the boards of the circuit board guide and fix parts. PCB is very strict in the depth and size of the countersunk hole, and its size should be limited to the tolerance area.

PCB back drilling

A back drilling hole is a hole controlled by a mechanical, which removes the copper plating of PTH hole stub that does not need to be guided and interferes with the signal, retain copper hole plating that needs to be used to guide the hole copper. The design principle of back drilling: Analysis of the characteristics of signal transmission from the hole angle. If it is designed as a through hole, the loop signal will be transmitted. The existence of a through hole can easily cause signal transmission, scattering and other problems, resulting in signal disturbance and distortion. When drilling the excess hole copper, the signal is returned according to the original path, which can cancel the inductance generated by the path signal and reduce the distortion of the signal to the greatest extent.

PCB press-fit hole

PCB press-fit holes refers to those holes that need not be soldering and can be directly inserted into components.hole size tolerance is more stringent than the general tolerance, the conventional tolerance of press-fit hole is +/-0/05mm, some of which can even reach +/-0.025mm, and most of press-fit holes are standard pin foot.

Posted on 12 Jun 2018
By info@kingsunpcb.com
In PCB knowledge

What jobs do we need to do before we choose the PCB factory?

We begin choose PCB manufacturer after a PCB be finished layout. What jobs do we need to do before we choose the factory?

1. Outputs gerber file and drilling file

Some engineer designed the PCB files and sent them to the PCB board factory directly. The PCB board factory has to transform the Gerber files on its own. Some companies require the conversion of PCB files to GERBER and drilled files to PCB factory. Because PCB engineers do not understand the functions and applications of electronic components, they will only produce according to the information provided by PCB. Maybe the GERBER file transferred from PCB factory is not what you want.

If the parameters of the components are defined in the PCB file at the time of design, they do not want these parameters to be displayed on the PCB finished products. If not specifically explained, the PCB factory engineers output these parameters to Gerber, this information will remain on the PCB finished product. Some engineers like to design metallized slot in the outline layer. If PCB spec instructions are not provided, PCB engineers may make the slot non metallized. If you convert your PCB files to GERBER files, you can avoid such incidents.

The GERBER file is an international standard drawing format file, which contains two formats of RS-274-D and RS-274-X, in which RS-274-D is called the basic GERBER format, and a D code file can be incidentally attached to a complete description of a graph. RS-274-X is called extended GERBER format, which contains D code information in itself. Commonly used CAD software can generate these two format files. Now it is generally required to produce GERBER files to the board plant in RS-274-X format.

How do you check the generated GERBER correctness? You can use the CAM350 software to import these GERBER files and D code files, you can see them on the screen or print them through the printer, then confirm them.

2. How to choose PCB manufacturer

The most challenging place for PCB is the contradiction between design and manufacturing cost capability. The multi-layer board can make use of narrow line space to complete the demanding signal quality. After the completion of PCB layout, it is perfect. But the problem is coming up, and sending out quotations to the PCB factory. 3 of the 5 companies have difficulty in feedback and exceed the technological capability. It is very important to understand the process capability of PCB board plant. You have to know if your PCB is designed and whether PCB manufacturer can produce it. A reasonable and optimal PCB is to take into account the cost and routing complexity. The more layers, the better the line, but the cost is high.
Understand each production cost of PCB plate plant: stacking, blind hole, hole, plug hole, back drilling, machining precision, drilling ratio requirement, line width and so on, can estimate the price at the initial stage of the principle map, even consider the cost in the design, so that the final product has the price competitive power.
PCB board actual production capacity inspection, line width check, line spacing, line hole distance and so on.
Produce PCB board file, produced by PCB manufacturer.

All these jobs be finished, you will get your own designs after a week.

Posted on 29 May 2018
By info@kingsunpcb.com
In PCB knowledge

What Is PCB Etching?

In printed circuit board manufacturing, printed circuit boards made with Multiwire board and Additive Process technology do not have to be etched. The printed circuit boards made by subtraction process need etching process to form conductive graphics. Under the protection of the graphic mask, the PCB etching removes the copper that is not needed on the copper-clad substrate by chemical reaction to form the required circuit pattern. As the mask of the graphic part of the circuit, it uses graphic transfer or screen printing to make the photoresist of the organic compound system or the surface of a metal anticorrosion layer to cover the circuit pattern to form an anticorrosion layer. Therefore etching process is an indispensable step in the manufacture of printed circuit boards. With the rapid development of microelectronic technology and the wide application of large scale integrated circuits and large scale integrated circuits, the width and distance of wire on printed circuit board are becoming smaller and smaller, and the density and precision of wiring are higher and higher. The precision and tolerance of etch are higher and more strict, and the quality of etching is better. The bad is directly related to the quality of the printed board. Therefore, to fully understand and master the corrosion mechanism of copper in various types of etchant, the choice of better etching solutions, methods and equipment is the necessary condition to meet the requirements of etching. In particular, the function and etching method of etching solution is the key to ensure the size accuracy of circuit graphics.

There are two kinds of resist layer on the circuit diagram, one is the organic film anticorrosion layer, the other is the metal coating anticorrosion layer. When choosing the etching solution, it is necessary to consider the anticorrosion protective layer suitable for the type of etchant. The etching speed is fast and can be easily controlled, the etching coefficient is large and the side corrosion is small; the etching solution can run continuously and regenerate, the amount of copper dissolving is large, the solution life is long, and the stability is good: the wide range of working conditions and the better washability: It should also consider the good working environment, easy recovery and reuse of copper, and easy treatment of sewage.

In the initial stage of printed circuit board manufacturing, the anticorrosion layer used on a single panel is a liquid photoinduced anticorrosion layer (bone glue, polyvinyl alcohol, etc.) with ink as an anticorrosion layer, and the etchant used is acid trichloride and other acid etchant. When making printed circuit boards with metallized holes, gold, tin, lead, tin and other metal resist layers are used. The type of etching solution suitable for metal resist is different from that of resist metal. Gold coating is used as an anticorrosive coating. It can be used as an etching solution or an alkaline etching solution. Tin lead alloy and tin coating are suitable for alkaline etching solution. At present, the corrosion resistant layers of tin lead alloy and tin are widely used as etchant of ammonia alkaline copper chloride, and the organic etch etching can be used in a series of hydrogen sulphate and nitric acid etchant. In general, etching rate can be continuously etched. The regeneration of the solution can be carried out automatically, and the etched copper can be recycled.

In the early etching process, the etching is carried out by immersion and agitation sputtering. The production efficiency is low and the etched product has poor precision. Later, the equipment of the horizontal jet is developed, which can be etched continuously, speed up, production efficiency and the precision of circuit graphics are greatly improved.

Posted on 28 May 2018
By info@kingsunpcb.com
In PCB knowledge

What is Embedded PCB Technology?

Nowdays the assembly density of components on PCB is getting higher and higher follow the miniaturization, thinning and high speed of electronic products. And the transmission speed of the electric signal is getting faster and faster, it is difficult to meet the higher assembly requirements only increasing the wiring density and multilayer of PCB. In order to improve the integrity of transmission signals, high frequency and high-speed digital signals in high-speed computing systems and communication devices are transmitted, It is usually achieved by strictly controlling the characteristic impedance (Z0) in the transmission line and using a large number of matched resistors or capacitors. However, such a large number of chip resistors and capacitors will occupy a large part of the PCB area and space, affecting the limit of PCB to achieve high density assembly. At the same time, these conductive holes and conductors used to match resistors (or capacitors) have inductive capacitance. It will affect the decoupling effect of signal transmission impedance and capacitance, thus generating the integrity of transmission line signals.

If these elements are embedded in the printed circuit board, the space for installing SMD on the same area will be greatly increased. At the same time, it can also improve the impedance matching requirements of signal transmission characteristics. In recent years, printed circuit boards with embedded components such as resistors and capacitors have developed rapidly. Although some technologies are not perfect at present, the superiority of it is more and more valued by the electronics manufacturing industry. As one of the development directions of printed circuit boards, it will become increasingly mature and widely used.

Types of printed versions embedded in passive components

Embedded passive PCB can be classified into four types according to their type and mode.

Embedded Resistor PCE :The passive element embedded in the printed board is the resistance.
Embedded Capacitor PCI: The passive element embedded in the printed board is the capacitance.
Embedded Inductor PCB: The passive element embedded in the printed board is the inductor.
Embedded Passive PCB: printed boards embedded in various passive components.

When PCB is embedded with two or three kinds of components, such as resistors, capacitors and inductors, it can be called passive PCB.

Application range, advantages and disadvantages of embedded passive printed boards

Application range

Embedded passive PCB is widely used at home and abroad, and is mainly used in computers (such as giant computer mainframe, information processor). PC card, IC card and all kinds of terminal equipment, communication system (such as cellular launch platform ATM system, portable communication equipment, etc.), test instrument and test equipment (such as IC scan card, interface card, load board tester), Aerospace electronic products (such as space aircraft, electronic devices on artificial satellites, etc.), consumer based electronic devices (such as potentiometers, heaters), medical electronic devices (such as scanners, ttms), and electronic control systems in military equipment (such as cruise missiles, radar unmanned reconnaissance machines, shields, etc.)

Advantages and disadvantages

Embedding a large number of embeddable passive elements into printed circuit boards (including HDI boards), making PCB components more lightweight and lightweight. Embedded printed boards with passive components have the following advantages:

Improving the degree of high density of PCB:

Because the discrete (non buried) passive components are not only assembled in large quantities, but also occupy a large amount of space on the printed board surface, such as the GSM phone contains more than 500 passive components, accounting for about 50% of the area of the printed board panel, such as embedding 50% of the passive components into the printed board (or HDI board). The size of the printed board surface can be reduced by about 25%, thus greatly reducing the number of through holes and reducing and shortening the connecting wires. It can not only increase the flexibility and degree of freedom of PCB design and wiring, but also reduce the amount of wiring and shorten the length of wiring, thus greatly increasing the degree of high density of printed board (or HDI board) and shortening the transmission path of the signal.

Improving the reliability of PCB assembly

Embedding the passive components into PCB can significantly improve the reliability of PCB (or HDUBUM) assembly. Because of this process, the welding (SMTAK PHT) point of the printed board surface is greatly reduced, thus the reliability of the board is improved and the probability of the failure caused by the welding point is greatly reduced.

In addition, buried passive components can be effectively protected and improved reliability. Because these passive components are embedded inside the PCB instead of discrete (or discrete) passive components, they are soldered (or bonded) by pins.

The connection pad on PCB surface will not be eroded or damaged by moisture or harmful gas in the atmosphere. Therefore, embedding passive components can significantly improve the reliability of PCB assemblies.

Improving the electrical properties of PCB assembly

Embedding passive components into high-density PCB makes the electrical performance of electronic interconnect improved significantly. Because it eliminates the need to connect the pads, wires and the wires formed after soldering. Any such loop will inevitably produce parasitic effects, namely stray capacitance and parasitic inductance. And this parasitic effect will also become more serious with the increase of the signal frequency or the forward time of the pulse square wave. Eliminating this type of fault will undoubtedly improve the electrical performance of PCB assemblies (signal transmission distortion is greatly reduced). At the same time, because the passive components are embedded inside the printed board, the surrounding is closely protected. It will not change its function value (resistance value, capacitance value and inductance value) because of the dynamic changes in the working environment, and make it in a very stable state, which is beneficial to improving the stability of the function of passive components and reducing the function of passive components. The probability of failure.

Saving the cost of product manufacturing

The cost of products or PCB assemblies can be obviously reduced by adopting this process. In the study of the radio frequency circuit (EP RF) model embedded in passive components, the printed board substrate (embedded in the same passive component) is equivalent to the low temperature co fired ceramic substrate (LTCC). According to the cost of the statistical component, the cost can be saved by 10%, the cost of the substrate can be saved by 30%, and the cost of assembly (welding) can be saved by 40% . At the same time, because the assembly process and the sintering process of the ceramic substrate are difficult to control, the printed board substrate embedded in the passive component (EP) can be completed by the traditional PCB manufacturing process, thus greatly improving the production efficiency.

Of course, any process has its limitations. The shortcomings of embedded PCB are:

One is that the passive components that are buried at present are small in function value. For the components of large resistance value, capacitance value and inductance value, it is necessary to develop passive component materials with large functional characteristics.

Secondly, it is difficult to control the error control of the function characteristic value of the embedded passive components, especially the plane type embedded passive component material with screen printing, which is more difficult to control the error of the function characteristic value error. Although laser technology can be used to repair and control the characteristic and functional error of embedded passive components, not all embedded passive components can be repaired by this method, so as to achieve the design requirements. The latest research of film resistance embedding method has greatly improved the accuracy of resistance value.

Posted on 25 May 2018
By info@kingsunpcb.com
In PCB knowledge

Characteristics Of Metal Core PCB

Heat dissipation

Conventional PCB substrates are generally hot undesirable conductors, The interlayer insulating material has a very slow heat emission. The internal heating of various electronic devices and power equipment can not be eliminated in time, result high speed components failure. But the metal core PCB has good heat dissipation. The metal core has high thermal capacity and high thermal conductivity, which can quickly dissipate the heat in the PCB. If the metal core is connected with the shell and the external radiator, the heat dissipation effect is better. Because the electronic equipment and communication system adopts metal core PCB, The fan in the equipment can be omitted, and the volume of the equipment is greatly reduced. The efficiency is improved, especially for the electronic equipment of closed chassis.

Thermal expansibility

Thermal expansion and contraction are the commonalities of matter, and the thermal expansion coefficients of different substances are different. PCB is a composite material made of resin, reinforced material and copper foil. The coefficient of thermal expansion is two opposite, in the direction of xY axis. The thermal expansion coefficient of PCB CTE is 13×10^-6~ 18×10^-6 /℃. In the direction of the thickness of the PCB (the direction of the Z axis) is 80×10^-6～90×10^-6/℃, and the CTE of copper is 16.8×10^-6/℃, The CTE of the flake ceramic is 6×10^-6/℃.From these data, it can be seen that the PCB metallized hole wall and the connected insulating substrate are quite different in the Z axis CTE. If the heat generated can not be eliminated in time, the thermal expansion and shrinkage will make the coating of the metallized hole wall crack or break. When the ceramic chip carrier is welded on PCB.Due to the difference between the device and the PCB material CTE, the fatigue failure of the solder joint will be caused by the long-term stress.

The thermal expansion rate of metal core PCB is small, and its size is much more stable with temperature than PCB of insulation material. Aluminum base PCB, aluminum sandwich PCB, the size change is only 2.5% to 3% from 30℃ to 140~150℃, It can meet the welding reliability requirements of ceramic chip carrier devices.

Magnetic shielding

Metal core PCB also has shielding effect, Especially the anti electromagnetic interference of CIC core plate is good, It can replace the radiator and other components, and effectively reduce the area of PCB. The effect of electromagnetic shielding, It can improve the electromagnetic compatibility of the products and reduce the production cost.

The use and characteristics of several common metal core substrates.

Copper base: Good thermal conductivity, used for heat conduction and electromagnetic screen cutting, but with high quality and high price.
Iron base: Anti electromagnetic interference, shielding performance is the best, but the heat dissipation is poor, the price is cheap.
Aluminum base: The heat conduction is good, the quality is light, and the electromagnetic shielding is good

Commonly used metal core clad foil boards include aluminum core, iron core (including silicon steel plate), copper core and CIC.

Aluminum substrate material

The most commonly used aluminum base materials for making metal core PCB are LF, L4M and LY12. The tensile strength is 294N / mm and the elongation is 5%. Commonly used thickness is 1mm, 1.6mm, 2mm, 3.2mm four specifications. The common aluminum layer is is 140um used in communication power supply, with copper foil on top and bottom.

Copper base material

The tensile strength of copper based substrates usually ranges from 245 to 313.6N / mm2. The extension rate is 12%, Common thickness is 1mm, 1.6mm, 2mm, 2.36mm, 3.2mm five types.

Iron base material

The most common is cold rolled steel plate used in production. It belongs low carbon steel with two kinds of thickness of 1mm and 2.3mm. Or use phosphorus containing iron base thickness of 0.5mm, 0.8mm, 1.0mm three types.

Copper foil

The back of the copper foil is chemically oxidized, galvanized and brass plated. The aim is to increase the strength of anti peeling. The thickness of copper foil is usually 17.5um, 35um, 75um and 140um.

Posted on 23 May 2018
By info@kingsunpcb.com
In PCB knowledge