BGA will become the main form of assembly in the future

Market demand for electronic products is small in volume, light in weight, easy to carry. This trend is driving semiconductor industry in high density assembly will continue to seek a new method of solving the problem. Many industry experts believe that, ball grid array BGA (ball grid array) components will become high density and high I / o applications of semiconductor component design breakthrough. Their reliability is rapidly increasing, a lot of companies that BGA will become the mainstream of the future assembly form.

The BGA concept increasingly popular. The so-called BGA is refers to the components of the contact neither lead nor pin, but the connection at the bottom of the device into an array like very small (diameter of 0.8mm) tin / lead alloy ball, pitch 1.5mm (0.060 inches), accordingly to provide reliable connection. This style of components not only for the single chip connection is ideal, and the high performance multi chip module (MCM) connection is also very reliable.

Very small diameter of tin / lead alloy ball instead of lead means can be removed by the lead coplanarity and skew caused most of the problems. With the increase of the number of I / O, BGA is not simply towards more and more fine pitch, but the use of contact spacing book of slightly larger than the fine pitch device spacing.Jedec note 1.0,1.27,1.5mm. currently being launched 1.27 and 1.5mm pitch instead of 0.5 ~ 0.4 mm fine pitch devices.

These components single chip and multi chip structure. This technique can be the I / O expansion to more than 1000. Estimated that at the end of this century, the future all ASIC applications will have 50% for 200 or more than 200 i/o. use of fine pitch devices, its fine wire is easy to damage and is extremely fine accurate placement and strict lead coplanarity.

There are three types of BGA. Another advantage of BGA assembly is adapted to existing SMT assembly process and equipment, that can use existing solder paste screen printing equipment, pick and place equipment and reflow soldering equipment. Due to the BGA average wirelength than equivalent I / O assembly line length, so it has better electrical characteristics.

FR4 PCB Board Manufacturing

Epoxy glass Burkina board, based on epoxy resin as the binder, the electronic-grade glass fiber cloth as a reinforcing material based substrate. It’s bonding sheet and the inner core thin CCL is an important base of manufacturing a multilayer printed circuit board. Mechanical properties of epoxy fiberglass cloth plate, dimensional stability, impact resistance, moisture resistance than paper substrates. It's electric excellent performance, high temperature, low environmental impact by the performance itself. In the process, other than the resin fiberglass cloth panels have great advantages. Epoxy fiberglass cloth panels, the most widely used product model for FR-4.

FR-4 material is a fire code rating, represents a material specification is meant a resin material through the combustion state must be self-extinguishing, it is not a material name, but a material grade. So now FR-4 grade material is typically used in circuit boards, there are many species, but most are based on the so-called four-function (Tera-Function) plus epoxy filler (Filler) and glass fiber made composite materials. These products are mainly used for double-sided PCB, a great amount. In recent years, due to the installation techniques and electronic products PCB technology development needs, it appeared high Tg FR-4 product.

FR4 PCB medium relative dielectric constant of air is 4.2-4.7. The dielectric constant with temperature changes within the temperature range of 0-70 degrees, the maximum variation range of up to 20%. Changes in the dielectric constant of the delay will result in a 10% change in the line, the higher the temperature, the greater the delay. Dielectric constant also changes with the signal frequency, the higher the frequency the smaller the dielectric constant. 100M the following can be used to calculate plate capacitance between 4.5 and delays.

General FR4 material PCB board signal transmission speed is 180ps / inch (1inch = 1000mil = 2.54cm). Surface generally, as the case may be, generally between 140 and 170.

Dielectric constant (Dk, ε, Er) determines the electrical signal propagation velocity in the medium. It is verse between Electrical signal propagation speed and proportional to the square root of the dielectric constant. The lower the dielectric constant is, the faster the signal transmission is.

The dielectric constant is not very easy to measure or definition, it is not only the characteristics of the medium itself, but also with the test methods, test frequency, material condition before testing and test related. Dielectric constant also with temperature changes, some special materials in development will take into account the temperature factor. Humidity is also an important factor in the impact of the dielectric constant, because the dielectric constant of water is 70, very little water It will cause significant changes.


In addition to the direct impact on the dielectric constant of signal transmission speed, it is still largely determines the characteristic impedance, in different parts so characteristic impedance matching is particularly important in microwave communication.

What to pay attention to SMT patch welding

SMT patch processing is the most electronic factory will be used in the placement technology, with high assembly density, light weight and other advantages, which can meet the requirements of miniaturization of electronic.And welding is a very important part in the processing of SMT patch, we need to understand the attention of its welding in order to avoid mistakes. What we should pay attention to SMT patch welding, here Wonderful PCB will give your the answer.

1. Temperature of the soldering iron head

In SMT welding due to the different temperature of the soldering iron head, the put in Rosin block will produce different phenomena.

Therefore, we must make it in the appropriate temperature, usually in Rosin melting faster and do not smoke when the temperature is the most appropriate.

2. SMT patch welding time
SMT welding time should be as far as possible to control the precise point, the general requirements from the heating point of welding to solder melting and welding points should be completed within a few seconds. In order to avoid a long time, the welding flux on evaporate completely, eventually lose their role to help, or because the time is too short, so that the temperature of the welding point is not up to the welding temperature.

3. The amount of solder and flux

Solder and flux are indispensable materials welding, reasonable selection of the solder and flux, is an important link to ensure the welding quality. For the usage of the solder and flux to control, too much will cause the solder joint coarse even next to the circuit and take the tin short circuit, may also in the process of mobile electric soldering iron solder drop caused by other parts of the short circuit; if too small, it can't cover the solder joint, the influence of welding firmness.

In the SMT welding process, we should also need to be careful not to touch welding point, especially in the welding point of the solders have not solidified completely and can not be freely moved welding of welded device and wire, otherwise, will point welding deformation,weld phenomenon, the influence of welding effect. Learn more about What is SMT technology here

FPC flexible printed circuit board material introduction

On the composition of FPC flexible printed circuit board material

Insulating Substrate

Insulating substrate is a flexible insulating film. As the circuit board insulating carrier, flexible dielectric thin film, the heat resistance of the comprehensive survey of the material requirements, covering shape performance, thickness, mechanical properties and electrical properties. Now engineering commonly used is film of polyimide (pi: polyimide with the, the name of the commodity, Kapton), ptfe:ployterafluoroethylene polyester (pet:polyester commodity name Mylar film and PTFE film. The general film thickness selection in the range of o.0127 o.127mm (0.5 ~ 5MIL). Polyimide film, polyester film and poly tetrafluoroethylene film performance comparison.

Adhesive sheet

Bonding sheet is adhesive film and metal foil, or bond films and film coverage (film). For the thin films deposited on different substrates can be used for different types of bonding sheet, such as polyester binder film and polyimide with bonding sheet is not the same, the polyimide substrate bonding sheet with epoxy and acrylic acid. Choose bonding sheet is focused on material flow and thermal expansion coefficient. No bonding sheet polyimide copper clad laminate, resistance to chemical and electrical performance is better.

Due to the low acrylic adhesive sheet of glass transition temperature, a large amount of contamination produced in the process of drilling is easy to remove, effect of metallized hole quality, as well as other adhesive materials to be unsatisfactory place, so multilayer flex circuit layer bonding piece of common polyimide material, since cooperating with polyimide substrate, the CTE (coefficient of thermal expansion (CTE) to overcome the size instability in multi-layer flexible circuit and other properties can satisfactory.

Copper foil

Copper foil is covered with adhesive in the substrate of the conductor insulating layer, after selective etching of the formation of conductive lines. This kind of copper foil most is the rolled copper foil (pcrca copper foil) or electrolytic copper foil (electrodeposited copper foil). The ductility of the wrought rolled copper foil and bending is better than that of the electrolytic copper foil, an extension of the rolled copper foil rate is 20% ~ 45%, the extension of the electrolytic copper foil rate is 4% ~ 40%. The thickness of copper foil is the most commonly used 35um (1oz), thin 18um o.5oz or thick 70UM (2oz), even 105um (for).

Coverage
The covering layer is an insulating protective layer covering the surface of the flexible printed circuit board, which can protect the surface of the conductor and increase the strength of the substrate.

First class is dry film type (coating), polyimide materials selection, without adhesive directly and after etching for the circuit boards in a laminated way pressing. The mulching requirements in the suppression of the pre forming, exposing welding part and therefore cannot meet more fine assembly requirements.

The second category is the photoreceptor development type. Sensitization development type of the first kind is covered dry film by film machine pressed in, by developing photosensitive exposed welding parts, to solve the problem of high density assembly; the second is the liquid screen printing covering materials, commonly used a thermosetting polyimide material, and photosensitive developing type flexible circuit board special solder resist ink.

More info on FPC board

Technology of SMT in PCB industry

SMT chip that is on the PCB Based on for processing series process referred to as the PCB (printed circuit board) for printing circuit board. (source: SMT is processing series process of PCB (printedcircuitboard) in the PCB infrastructure)


SMT is (surface mount technology) (an acronym for surface mounted technology), the electronic assembly industry in one of the most popular and a technical process. Electronic circuit SMT (surface mount technology, SMT), said for surface mount or surface mounted technology. It is a no pin or short lead surface mount components (SMC / SMD, the Chinese call sheet components) installed on the printed circuit boards (printed circuit board, PCB ) surface or other surface of the substrate, welding assembly of the circuit is connected by reflow soldering or other methods.

Usually we use electronic products are by the PCB and all kinds of capacitors, resistors and other electronic components according to the design of the circuit design, so all kinds of electrical appliances need different kinds of SMT processing technology to process.

SMT basic elements: the process of solder paste printing / parts mount -->AOI optical inspection / maintenance / return / welding plate.

Some people may ask answer electronic components why to do so complicated?? this fact and the development of our electronic industry is closely related to, today, the electronic products, the pursuit of miniaturization, previously used perforation plug-in components has been unable to narrow. Electronic product function can more complete, the integrated circuit (IC) has no perforated elements, especially on a large scale, highly integrated IC, had to use surface mount components. Product batch, automatic production, the factory to with low cost and high yield, produce high quality products to meet customer needs and strengthen the development of the market competitiveness of electronic components, integrated circuit (IC) open , semiconductor materials of diverse applications. Electronic technology revolution is imperative, chasing the trend. Can imagine, in Intel, amd the CPU, image processing production process of the component manufacturer strives to 20 nanometers, the SMT surface assembly technology and development is not to the situation.

SMT processing has the advantages of high density assembly, electronic products, small size, light weight, the volume and weight of the SMD components only traditional cartridge elements about a tenth of the common SMT, electronic products smaller 40% ~ 60%, the weight is lightened. High reliability and anti vibration can. Solder joint defect rate low. High frequency characteristics. Reduce the electromagnetic and radio frequency interference. Easy to realize automation, improve production efficiency. Reduces costs by up to 30% to 50%. Save material, energy, equipment, manpower and time.

Source: What is SMT Technology

3 PCB Design Experience

1. if the PCB design of the circuit system contains the FPGA device, it is necessary to use the II quartus software to verify the distribution of the pin before drawing schematic diagram.

2. 4 layer PCB board from top to bottom is as follows: the signal level, power supply and a signal plane layer; 6 layers from top to bottom in turn: signal level, signal in electric layer, signal electric layer, power supply, signal plane layer 6 layer above the plate (advantage is: anti radiation interference), priority in their choice of electric layer wiring, walk not to open plane layer prohibited line away from the ground or power supply.

3. Multiple power system wiring, such as FPGA DSP systems do six plates, at least in general will 3.3V 1.2V at 1.8V 5v.3.3v is generally the main power supply, direct shop power supply layer, through holes easily buton global power supply network.

5V generally may is the power input, need only in a small area of the copper paving. And as far as possible (you ask me the more thick, crude more rough, the thick, the better) 1.2V and 1.8V is separated from the kernel power (if the line is connected with the way will encounter great difficulties in the face of BGA devices), layout as 1.2V and 1.8V, and let 1.2V and 1.8V connected component placement in a compact area, the use of copper skin connection.

In short, because the power network throughout the entire PCB, if the use of the way the line will be very complex and will be around a long way, the use of copper clad method is a good choice!

Chinese and foreign current situation of printed circuit board industry

Printed circuit board as an important electronic components, electronic components supporting body. Due to its important role in the field of electronic components, so it is many people to become "electronic carrier". With the development of science and technology, printed circuit board is widely used in military, communications, medical, power, automotive, industrial control, smart phone, wear and other high-tech fields.

Therefore, PCB board level of production technology has gradually become an important indicator to measure the level of a national science and technology. However, compared with the developed countries of the printed circuit board industry development status and trends, China printed circuit board industry in which stage, there is what problem, how should solve. This is this article tries to answer the question.

1 Development status of printed circuit board industry in China

At present, the global printing circuit board industry development has stepped on a relatively stable period of development, has been formed, including Hong Kong, China, Japan, Taiwan, China, South Korea, the United States, Germany and the Southeast Asian region, including seven major production centers, of which Asia accounted for 79.7% of global gross domestic product.

China due to the distribution in the industrial, manufacturing cost have the advantage, has become the world's most important printed circuit board production base, 2013 circuit board output of China has occupied more than 44.2% of global output, but individual enterprises in China market occupies a smaller share, do not have a strong ability to lead to the market.

2 Development status of global printed circuit board industry

Since the middle period of the fifties of the 20th century, the PCB technology began to widely used. At present, PCB has become the "mother" of the electronic products, its applications almost penetration in the electronics industry in each end of the field, including computer, communication, consumer electronics, industrial control, medical instruments, national defense, aerospace and other fields. Future with the development of a new generation of information technology industry, smart phones, automotive electronics, led, IPTV, digital television and other new electronic products continue to emerge, market and application of PCB products will continue to expand.

In recent years, the global PCB industry overall is steady growth in 2009 due to the impact of the global financial crisis, PCB output value has declined, 2010 with global macro economy to improve step by step, PCB industry began to recover, the annual output value of 524.68 billion U. S. dollars, more than in 2009 increased substantially 27.33%.

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