Archives for PCB Facts

10 Cool Facts About PCBs

1. Why they’re green

When talking about PCBs, I believe that iconic dark green color will come to your mind. Have you ever wondered why this color? The green that you see is actually the color of the soldermask showing through the glass. When the origins of the use of the green is concerned, there are a few theories.

Some speculate that green was the regulation standard when PCBs were used by the American military, and the use of it spread from there. It has also been suggested that green could have been the color of the original solder mask resins, and that we continue to use green as a matter of convention, despite these materials are no longer used. Actually in modern circuits we see a soldermask made in any color, including yellow, black, and blue. Just name a few. However, green has worked well for us so far, and there is a cutting edge when using green, making it particularly easy for engineers to see faults in the traces. Maybe that’s why a lot of manufacturers tend to stick with it. I hope that can explain why the green comes to mind when people talk about PCB.

2. Who invented them?

Paul Eisler, an Austrian inventor, is generally known to get accredited for the invention of the PCB although the development leading up to the invention can be traced as early as 1890s. Eisler developed the first PCB when working on a radio set in 1936. However, PCBs saw mass usage till 1950s. And it got significant increase in popularity from there.

3. They are everywhere!

There is no doubt about the popularity of Printed Circuit Board. You pick up an electronic gadget at your hand and it makes use of one right now. There is a big chance that you are reading this from a device that contains a PCB. PCB has become a really integral aspect of modern tech, and as PCB technology itself is constantly evolving, we can not see any chance that any other creations will be replacing them in the near future.

4. They’re designed using CAD

You might not know that PCBs are designed using CAD, or computer aided design. Technicians use CAD programs to design both the schematic and the layout of the Printed Circuit Board. This allows the board design to be tested, checking that all the traces are properly connected before the PCBs are physically made. It decreases the possible errors in PCB manufacturing.

5. Surface mount technology

Surface mount technology (or SMT in acronym) is the most common manufacturing technique used to make modern PCBs. SMT became widely used in the 1980s and quickly replaced its predecessor, the through-hole method, which had been slow and incurred many errors. Whereas with through-hole the components had to be attached to the board by inserting component ‘leads’ into holes, SMT makes them glued onto pads on the PCB’s surface.

6. Traces other than wires
You probably know that electronic devices most commonly use wires as a means of transmitting energy. However, PCBs are exceptional to this convention. PCBs use copper traces instead of wires to transport electrons. Using copper traces in the place of wires allows PCBs more compactability, as the flat traces take up a lot less room. It also means that they can be made using through-hole technology, as the copper can easily transfer through a hole in the circuit board.

7. There are a lot of potential components

There are probably more components used in PCBs than you thought, and they all have their own individual properties. The list includes (but is not limited to) resistors, potentiometers, capacitors, inductors, relays, batteries, fuses, transformers, diodes and transistors.

8. Silkscreens

Have you ever wondered about the white etchings that you seen on top of the green PCB soldermask? This is the silkscreen, and it is used on the component side of the circuit board to help identify components and other PCB information. The white text can be silk screen printed, which is the origin of the name. However it tends to be printed using digital by ink-jet printers nowadays.
9. They can be completely personalised

You can order them to suit the specifications you need from the PCB manufacturers. But there is no need to make every PCB to a unique specification since custom PCBs are costly in time and money.

10. The technology is always changing

PCBs have changed hugely since Paul Eisler invented it in 1936. Currently they’re much more smaller, faster, and efficient to build. However PCB technology is always evolving. Right now scientists are working on making PCBs that are biodegradable which means more environmentally friendly. Similarly, the development of the material ‘graphene’ could change the ways in which our electronics operate. PCBs are never static; the technology is always developing to get improved.

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A Review of Flexible Circuit Technology and its Applications

Flexible circuits are a high-growth technology in the area of electrical
interconnectivity and look set to deliver improved performance against the
demands of many twenty-first century products.

The compact nature of flexible circuits and the high electrical-connection density
that they can achieve offer considerable weight, space and cost savings over the
use of traditional rigid printed circuit boards, wire and wire harnesses. The
technology offers the potential of reducing the total costs of electrical
interconnections by up to 70% and reducing cable and wiring use by up to 75%
when married with an appropriate application. It is to be noted that flexible printed
circuits have replaced hand-built wire harnesses in many applications.

This review will provide a basic assessment of Flexible Printed Circuits (FPC)
technology, flex circuit construction and manufacture, flex circuit materials,
market developments, technology developments within the FPC field, along with
major applications of the technology. It is hoped these applications exemplify how
FPC has the potential to offer product developers and designers significantly
more design freedom, enabling them to meet the higher circuit-density demands
of tomorrow¡¯s electronic systems.

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The Whole History of Printed Circuit Boards

What is Printed Circuit Board
Before we start to talk about the history of printed circuit boards, we need to figure out firstly what a Printed Ciruit Board (usually called PCB) is. A printed circuit board (PCB) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from copper sheets laminated onto a non-conductive substrate. PCBs can besingle sided (one copper layer), double sided (two copper layers) or multi-layer (outer and inner layers). Multi-layer PCBs allow for much higher component density. Conductors on different layers are connected with plated-through holes called vias which were covered in previous blogs. Advanced PCBs may contain components – capacitors, resistors or active devices – embedded in the substrate.

Printed circuit boards are applied in various industries and business. It requires the additional design effort to lay out the circuit, but manufacturing and assembly can be automated. Manufacturing circuits with PCBs is cheaper and faster than with other wiring methods as components are mounted and wired with one single part. Furthermore, operator wiring errors are eliminated.

PCBs are grouped into 3 main types, namely Single Sided Board, Double Sided Board, and Multi Layered Board.

Single Sided Board is the least complicated of the Printed Circuit Boards, since there is only a single layer of substrate. All electrical parts and components are fixed on one side and copper traces are on the other side.

Double Sided Board is the most common type of board, where parts and components are attached to both sides of the substrate. In such cases, double-sided PCBs that have connecting traces on both the sides are used. Double-sided Printed Circuit Boards usually use through-hole construction for assembly of components.

Multi layered PCB consists of several layers of substrate separated by insulation. Most common multilayer boards are: 4 layers, 6 layers, 8 layers, and 10 layers. However, the total number of layers that can be manufactured can exceed over 42 layers. These types of boards are used in extremely complex electronic circuits.

PCB History
Point to point construction was used before printed circuits became the popular component used in electronics. It meant a few extremely bulky and unreliable designs that required large sockets and regular replacement. However, most of the issues were addressed when PCBs went into regular production.

For prototypes, or small production runs, wire wrap or turret board can be more efficient. Predating the printed circuit invention, and similar in spirit, was John Sargrove’s 1936–1947 Electronic Circuit Making Equipment (ECME) which sprayed metal onto a Bakelite plastic board. The ECME could produce 3 radios per minute.

The Austrian engineer Paul Eisler invented the printed circuit as part of a radio set while working in England around 1936. Around 1943 the USA began to use the technology on a large scale to make proximity fuses for use in World War II. After the war, in 1948, the USA released the invention for commercial use. Printed circuits did not become commonplace in consumer electronics until the mid-1950s, after the Auto-assembly process was developed by the United States Army. At around the same time in Britain work along similar lines was carried out by Geoffrey Dummer, then at the RRDE.

Originally, every electronic component had wire leads, and the PCB had holes drilled for each wire of each component. The components’ leads were then passed through the holes and soldered to the PCB trace. This method of assembly is called through-hole construction. In 1949, Moe Abramson and Stanislaus F. Danko of the United States Army Signal Corps developed the Auto-assembly process in which component leads were inserted into a copper foil interconnection pattern and dip soldering. The patent they obtained in 1956 was assigned to the U.S. Army. With the development of board lamination and etching techniques, this concept evolved into the standard printed circuit board fabrication process in use today. Soldering could be done automatically by passing the board over a ripple, or wave, of molten solder in a wave-soldering machine. However, the wires and holes are wasteful since drilling holes is expensive and the protruding wires are merely cut off.

From the 1980s small surface mount parts have been used increasingly instead of through-hole components; this has led to smaller boards for a given functionality and lower production costs, but with some additional difficulty in servicing faulty boards.
PCB Future
Currently, most circuit boards use multi-step methods such as conventional vacuum deposition and photolithographic patterning. However, these methods have certain disadvantages since they require a high processing temperature, involve toxic waste, and are costly. We have seen advances in technology in previous years and it’s not hard to imagine PCBs will soon be revolutionized. With the use of 3d printing become more mainstream ‘3d printing’ a printed circuit board has become realized.

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