Printed Circuit Board

A printed circuit board, or PCB, is a self-contained module of interconnected electronic components found in devices ranging from common beepers, or pagers, and radios to sophisticated radar and computer systems. The circuits are formed by a thin layer of conducting material deposited, or "printed," on the surface of an insulating board known as the substrate. Individual electronic components are placed on the surface of the substrate and soldered to the interconnecting circuits. Contact fingers along one or more edges of the substrate act as connectors to other PCBs or to external electrical devices such as on-off switches. A printed circuit board may have circuits that perform a single function, such as a signal amplifier, or multiple functions.
There are three major types of printed circuit board construction: single-sided, double-sided, and multi-layered. Single-sided boards have the components on one side of the substrate. When the number of components becomes too much for a single-sided board, a double-sided board may be used. Electrical connections between the circuits on each side are made by drilling holes through the substrate in appropriate locations and plating the inside of the holes with a conducting material. The third type, a multi-layered board, has a substrate made up of layers of printed circuits separated by layers of insulation. The components on the surface connect through plated holes drilled down to the appropriate circuit layer. This greatly simplifies the circuit pattern.
Components on a printed circuit board are electrically connected to the circuits by two different methods: the older "through hole technology" and the newer "surface mount technology." With through hole technology, each component has thin wires, or leads, which are pushed through small holes in the substrate and soldered to connection pads in the circuits on the opposite side. Gravity and friction between the leads and the sides of the holes keeps the components in place until they are soldered. With surface mount technology, stubby J-shaped or L-shaped legs on each component contact the printed circuits directly. A solder paste consisting of glue, flux, and solder are applied at the point of contact to hold the components in place until the solder is melted, or "reflowed," in an oven to make the final connection. Although surface mount technology requires greater care in the placement of the components, it eliminates the time-consuming drilling process and the space-consuming connection pads inherent with through hole technology. Both technologies are used today.
Two other types of circuit assemblies are related to the printed circuit board. An integrated circuit, sometimes called an IC or microchip, performs similar functions to a printed circuit board except the IC contains many more circuits and components that are electrochemically "grown" in place on the surface of a very small chip of silicon. A hybrid circuit, as the name implies, looks like a printed circuit board, but contains some components that are grown onto the surface of the substrate rather than being placed on the surface and soldered.
Wonderful PCB (HK) Limited, with over 15 years experience of producing PCB, fabricates printed circuit boards for customers in many industries worldwide, including communications/telecom/IT, medical electronics, consumer electronics (mobile phones, computers, LED lighting, etc.), and the automobile industry. We supply high-precision, high-density, double-sided and multilayer custom PCBs and PCBA services for customers in many countries.

Repairing printed circuit boards - tips by Exception PCB

PCBs, or printed circuit boards, have revolutionised the electronic industry; however they lack the robustness of the earlier, steel-chassis, hardwired equipment, driving them to be much easier to crack. Restoring a circuit board needs a particular level of analytical ability, along with the skill to handle each element in the correct way.

Without having a thorough knowledge of the way a circuit board works, experts from Exception PCB express that diagnosing the trouble will be a problem. For PCBs that are especially complex, you might also need an oscilloscope to discover signals at different points, so as to discover the section which is creating the problem. Once this component has been discovered, it will then have to be replaced. Here, Exception PCB provides you with a brief guide on how to do this.

As outlined by Exception PCB, with the majority of passive (and occasionally active) components, a similar, as opposed to an exact copy of the broken element can be used as a replacement. You will find, for example, several unique versions of voltage regulators available, and one version can easily be swapped for another in a PCB. However, broken active components that have a very specific function (for example, audio amplifier chips) must be replaced with an exact copy.

After you have acquired the right replacement, you'll have to place the PCB on a flat surface for the fix. Exception PCB says that you might use tape to stick the board on both sides to the surface, to ensure that it doesn't move whilst you are carrying out the replacement. Pull the damaged component off the board very delicately, using tweezers. Next, switch on your soldering iron and set it to about 400 degrees Celsius.

Take some copper wire and put it on the pads of the PCB where the component was, and use the soldering iron to heat it. Wonderful pcb that any surplus solder remaining on these pads could be absorbed by the copper. Get in line the leads of the replacement component with the board's pads, taking a look at to make sure that the element is aligned as it needs to be. Then, use the soldering iron and the solder to join the leads with the corresponding pads on the board. 

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FPC compared with Rigid PCB

FPC is an abbreviation from flexible circuit board, the update products after universal application of rigid PCB. In dictionary, FPC is a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide, PEEK or transparent conductive polyester film.

Flexible printed circuit boards (FPCs) are applied to various electronic devices due to their mechanical characteristics and are indispensable to electronic devices requiring system miniaturization, weight reduction and multi-functionality. Examples of applications for FPCs include cell-phone liquid crystal display enclosure, hinge parts, keypad, battery enclosure and interface components. FPCs are also used in optical pickup and device interfaces inside hard disk drives, digital still cameras and digital camcorders. By now, we could see that compared with rigid PCB, FPC is newly innovated connection mode between electronic components. Flexible PCB market now is poised for more growth. 2012 was a bumper year for flexible printed circuit board manufacturers, a new report says. The global flex circuit market reached $10.68 billion, up 15.2% from 2011, says Research and Markets. Moreover, FPC will maintain the strong growth momentum in 2013, Research and Markets said. The global market is expected to grow another 8.9% year-over-year to $11.63 billion this year.

But why make FPC market growing and keep prosperous in the following years? As we all know, the electronic market is pursuing portable and high density products. The traditional rigid PCB cost too much space in a circuit board and has limited space for mounting components, which cannot meet the requirement of modern development tendency. So FPC takes an advantage of opportunity to grow. Of course, there’re several reasons that the continuous boom of FPC.

Weight& Space-saving:
Flexible PCBs are with thinner board thickness. Today, the most common flexible printed circuit substrates are 12.5 - 25 µm thick, with the trend toward even thinner materials. Two primary types of copper foil are used for flex: electrolytic copper foil and rolled copper foil. Electrolytic copper foils typically come in thicknesses of 18 or 12 µm; while most rolled copper foils are 18 µm thick, which could be light weight. It can be bent, rolled, folded freely, can be arranged randomly according to the space, can be moved and stretched in 3-D space, then integrate the components assembly and wiring connection.

Better Electrical Performance:
The flexible circuit provides good electrical performance. Lower dielectric constant allows electrical signals to transmit quickly. Good thermal performance makes the assembly easy to cool. Higher glass transfer temperature or melting point makes the assembly work well at higher temperature.

Thermal and Mechanical Characteristics
Flexible circuits commonly pass through different electrical, thermal, and mechanical environments. For example, the basic disk drive circuit moves back and forth millions of time over a rotating platter. Electrically, the flexible printed circuit compromises its signal integrity each time a trace carrying a signal is moved with respect to the surrounding electrical environment. Thermally, the circuit is exposed to the heat generated within the disk drive enclosure. Mechanically, the circuit works like a spring, either resisting or adding force to the mechanical movement.

Conclusion
Flexible circuitry is a medium that offers many advantages over traditional interconnection methods and, in many cases, is the only viable solution. When deciding whether to use flexible or traditional wiring interconnects, several factors need to be considered. If the application requires high packaging density, dynamic flexing, bonding sites for digital devices, and high reliability over time, then flexible circuitry is probably the best choice.

CES 2015: The future of wearable technology

Flexible devices for clothing, virtual-reality contact lenses and tools to help hearing impediments are some of the futuristic use cases for rapidly emerging wearables.

"We should not be trying to make tech wearable, but rather make wearable things technology-enabled," according to Mike Bell, the vice president and general manager of Intel’s new devices group.
Speaking in Las Vegas today on a CES 2015 panel about the growth of wearables, Bell discussed the challenges PCB board assembly and brands in the space must overcome to break into the mainstream.
He said a "cellphone on the wrist" [the smartwatch has become the poster child for wearables] is not what people want, and wearable tech will start moving into items like jewellery and watches.
Wearable tech gets its share of bad press for a wide range of reasons, including its failure to look good and demonstrate utility for consumers. Reports have shown that current devices, such as fitness trackers, are often abandoned several months after use.
Despite the challenges the category faces, the panellists were bullish on wearable tech’s future, confident the devices are not a technology fad.
Christopher Glode, the general manager at Under Armour Connected Fitness, said: "The market valuation of wearables is not really relative to the amount of hype they get, but real markets are being created around wearables now.
"Sensors are getting smaller, batteries are lasting longer and the technology is evolving very, very quickly, piggybacking on smartphones, which means more things are possible now."
Bell added that wearable devices are more accepted these days because of the rise of smartphones, legitimising the need for consumers to have a device with them all the time.
But wearables will not replace smartphones any time soon, the panel argued.
"The phone will become even more important as a hub for experience," Glode said.
Carmichael Roberts, a partner at North Bridge, the venture capitalists, said that wearable tech would continue to innovate in the direction of something "invisible, seamless, comfortable and very personal," blurring the boundary between humans and computers.
"People won’t think about it, like they don’t think about having tattoos on their skin, like a stamp or a sticker," he said.
Limor Schafman, the founder and chief executive of GlobeShift, said the major future developments in the wearables space would be in flexible wearables that can become part of clothing, contact lenses with virtual reality and technology to help people with hearing impairments.
"There is no limit to the imagination of what is possible," Schafman said. "What is fascinating is that the technology is here. Now, what do we do with it?"
This story has been taken from Campaign US.
This article was first published on campaignlive.co.uk

Why use surface mount technology (SMT)?

Currently, advanced electronic products, especially in the computer and communications electronics products, has been widely used in SMT technology. SMD devices on year rise in international production, but production is declining conventional device, so as time goes into between, SMT technology will become increasingly popular.
So what is the advantage of SMT?
1,The pursuit of the miniaturization of electronic products, perforated and plug components used previously been unable to narrow.

2, The electronic product features become more complete, integrated circuit (IC) is no longer used by the piercing element, especially in large-scale, highly integrated IC, had to use surface mount components.

3, Bulk products, production automation, factory should take a low-cost high-volume, producing high quality products to meet customer demand and enhance market competitiveness

4, The development of electronic components, integrated circuits (IC) development, multi-application of semiconductor materials

5, Electronic technology revolution is imperative, chasing the international trend

SMT has become a mainstream technology in the era of high-density, due to the use of SMT technology, PCBA  also follow up and get rapid development. SMT market share surge makes more stringent, good PCBA SMT is a prerequisite for success. SMT mainly from the process to control the quality of the process. Today we will introduce single Sided SMT assembly process.

Single Sided SMT assembly process：

Incoming inspection -> screen printing solder paste (dot patch glue) -> patch -> drying (curing) -> reflow soldering -> Cleaning -> Test -> Rework

why do you want to use the halogen free material？

With the development of the industry, we are increasingly demanding to PCB material.
Electronic waste, bromine and chlorine compounds plastic products containing halogen flame retardant,

PVC, when these products waste burning, easy to produce harmful substances dioxin and acid gas (HCl),

through the biological accumulation, damage to the environment and human health, the United Nations

international environmental planning has its list of persistent organic pollutants (pops).
Halide widely exist in printed circuit board, welding mask, molding compounds, connectors, and other

common electronic products.Such as printed circuit boards in flame retardant containing halogen

material, PBB and PBDE toxicity is the most care about people.Circuit boards and electronic products

containing halogen in the case of incomplete combustion will produce many byproducts, including

dioxins, dioxin and furan compounds (furan - like compound), and acid or corrosive gas, these

potentially harmful to environment and human health.At present most of the electric power and

communication cable containing halogen, the cable will emit poisonous fog when burnt chemicals.In the

event of fire, acid gases from the burning of cables will damage people's nose, mouth and throat,

smoke can also make people lost, is difficult to escape the scene of the fire.So the EU ROHS

regulations banning in printed circuit board using PBB and PBDE contains both halide material.Now

someone is trying to contain halogen in electronic devices limit the use of all materials.When

burned, they argue, electronics, bromide material will generate toxic dioxins.They called for a ban

on the use of containing halogen material beyond the ROHS initially limit PBB and PBDE.


Halogen free may be after July 1, 2006 ROHS (harmful substances limits) instruction since electronic

industry and a green revolution.Compared to the dangers of halide, ROHS directive restricting the use

of six kinds of harmful substances of Cd and Pb (lead, cadmium, mercury, Hg, hexavalent chrome CR6, +

4 kinds of heavy metals and  PBDE, two kinds of flame retardants polybrominated biphenyl PBB) risks

more spectacularly.


Among them, the lead can harm the nervous system directly;Cadmium can cause harm to the bone,

kidneys, the respiratory system.Mercury will harm the central nervous system and kidney

system;Hexavalent chromium can cause inherited gene defects;  PBDE and polybrominated biphenyl are

strong carcinogenic and teratogenic substances.


From lead free and ROHS to halogen free to Norway for POHS instructions to ban the use of 18 kinds of

harmful substances, increasingly stringent environmental requirements for the materials not only can

significantly reduce the pollution to the environment of electronic products, also can effectively

protect our health.