Showing posts tagged 'transistors'
22 June 2022
Resins and coatings for electronic components
Printed circuit boards (PCBs) are the core of many electronic devices and contain electronic components like capacitors, transistors and fuses. As such, keeping them safe and protecting them from damage is key to the continued working of electronic devices. Resins and conformal coatings can be used for this purpose.
Resins are the more sturdy, heavier option in terms of coatings. This is a great choice when protecting a PCB from adverse conditions and insulating it from potential physical damage.
Within the range of resins used, there are three main types that are used, with each suited to certain PCBs.
This compound is well-suited for potting electronics, and protects components against moisture and mechanical damage coming from vibrations or shocks.
Depending on if there are amines (curing agent) mixed with the resin the curing time of the PCB can differ. Something to watch out for is the exothermic reaction cause by the curing. Although this can be mitigated, there is a risk of damaging the component.
The pricier cousin of epoxy resin, polyurethane can also protect PCBs against moisture, as well as high temperatures and UV. Most resins have a maximum temperature tolerance of 130⁰C. However, polyurethane can cope with temperatures of up to 150⁰C if formulated well.
This maximum temperature is in part thanks to the resin having a lower exothermic rate compared to epoxy. Polyurethane is also more flexible, so is favoured when it comes to potting delicate components.
Silicon also protects against UV light, and so is often used in LED applications where the change in the colour of the LED needs to be minimised.
Silicon is the most expensive of the three but is not as popular as its counterparts. The material thrives when it comes to high operating temperatures and heat-sensitive components, thanks to its low exothermic temperature.
While resins are thick, durable and designed for high levels of stress, conformal coatings are thinner, lighter and are transparent.
Thanks to the tiny layer of coating, usually applied with a paint brush or spray, this kind of coating is a lower-risk alternative than a heavy resin for fragile components.
The coating can be altered or removed more easily than the resin too, and the curing time is massively reduced. However, alongside this the component is more exposed and has a lower level of protection. This makes these coatings more useful for PCBs that will face shorter exposures.
Do your own research
Any coating of a PCB should be carefully considered depending on the purpose of the circuit board, the conditions and stresses it will face, and whether it already has a coating on it. If this is the case, chances are this original coating was meant as the PCB’s primary layer of protection.
Speaking of protection, Cyclops quality checks all of the electronic components it supplies. This protects its customers from damaged parts and counterfeits. For an extra layer of protection in your electronic component supply chain, contact Cyclops today.
This blog post is designed to be informative and is in no way offering advice or guidance on how to coat electronic components.
11 May 2022
What are GaN and SiC?
Silicon will eventually go out of fashion, and companies are currently heavily investing in finding its protégé. Gallium Nitride (GaN) and Silicon Carbide (SiC) are two semiconductors that are marked as being possible replacements.
Both materials contain more than one element, so they are given the name compound semiconductors. They are also both wide bandgap semiconductors, which means they are more durable and capable of higher performance than their predecessor Silicon (Si).
Could they replace Silicon?
SiC and GaN both have some properties that are superior to Si, and they’re more durable when it comes to higher voltages.
The bandgap of GaN is 3.2eV and SiC has a bandgap of 3.4eV, compared to Si which has a bandgap of only 1.1eV. This gives the two compounds an advantage but would be a downside when it comes to lower voltages.
Again, both GaN and SiC have a greater breakdown field strength than the current semiconductor staple, ten times better than Si. Electron mobility of the two materials, however, is drastically different from each other and from Silicon.
Main advantages of GaN
GaN can be grown by spraying a gaseous raw material onto a substrate, and one such substrate is silicon. This bypasses the need for any specialist manufacturing equipment being produced as the technology is already in place to produce Si.
The electron mobility of GaN is higher than both SiC and Si and can be manufactured at a lower cost than Si, and so produces transistors and integrated circuits with a faster switching speed and lower resistance.
There is always a downside, though, and GaN’s is the low thermal conductivity. GaN can only reach around 60% of SiC’s thermal conductivity which, although still excellent, could end up being a problem for designers.
Is SiC better?
As we’ve just mentioned, SiC has a higher thermal conductivity than its counterpart, which means it would outlast GaN at a higher heat.
SiC also has more versatility than GaN in what type of semiconductor it can become. The doping of SiC can be performed with phosphorous or nitrogen for an N-type semiconductor, or aluminium for a P-type semiconductor.
SiC is considered to be superior in terms of material quality progress, and the wafers have been produced to a bigger size than that of GaN. SiC on SiC wafers beat GaN on SiC wafers in terms of cost too.
SiC is mainly used for Schottky diodes and FET or MOSFET transistors to make converters, inverters, power supplies, battery chargers and motor control systems.
14 April 2022
How transistors replaced vacuum tubes
Electronics has come on leaps and bounds in the last 100 years and one of the most notable changes is the size of components. At the turn of the last century mechanical components were slowly being switched out for electrical ones, and an example of this switch was the vacuum tube.
A lightbulb moment
Vacuum tubes were invented in the early 1900s, and the first ones were relatively simple devices containing only an anode and a cathode. The two electrodes are inside a sealed glass or aluminium tube, then the gas inside would be removed to create a vacuum. This allowed electrons to pass between the two electrodes, working as a switch in the circuit.
Original vacuum tubes were quite large and resembled a lightbulb in appearance. They signalled a big change in computer development, as a purely electronic device replaced the previously used mechanical relays.
Aside being utilised in the field of computing, vacuum tubes were additionally used for radios, TVs, telephones, and radar equipment.
Apart from resembling a bulb, the tubes also shared the slightly more undesirable traits. They would produce a lot of heat, which would cause the filaments to burn out and the whole component would need to be replaced.
This is because the gadget worked on a principle called thermionic emission, which needed heat to let an electrical reaction take place. Turns out having a component that might melt the rest of your circuit wasn’t the most effective approach.
Transistors came along just over 40 years later, and the vacuum tubes were slowly replaced with the solid-state alternative.
The solid-state device, so named because the electric current flows through solid semiconductor crystals instead of in a vacuum like its predecessor, could be made much smaller and did not overheat. The electronic component also acted as a switch or amplifier, so the bright star of the vacuum tube gradually burned out.
Sounds like success
Vacuum tubes are still around and have found a niche consumer base in audiophiles and hi-fi fanatics. Many amplifiers use the tubes in place of solid-state devices, and the devices have a dedicated following within the stereo community.
Although some of the materials that went into the original tubes have been replaced, mostly for safety reasons, old tubes classed as New Old Stock (NOS) are still sold and some musicians still prefer these. Despite this, modernised tubes are relatively popular and have all the familiar loveable features, like a tendency to overheat.
Don’t operate in a vacuum
Transistors are used in almost every single electronic product out there. Cyclops have a huge selection of transistors and other day-to-day and obsolete components. Inquire today to find what you’re looking for at email@example.com, or use the rapid enquiry form on our website.
23 March 2022
The History of Transistors
Transistors are a vital, ubiquitous electronic component. Their main function is to switch or amplify the electrical current in a circuit, and a modern device like a smartphone can contain between 2 and 4 billion transistors.
So that’s some modern context, but have you ever wondered when the transistor was invented? Or what it looked like?
Going way back to when Ohm’s Law was first discovered in 1820s, people had been aware of circuits and the flow of current. As an extension of this, there was an awareness of conductors.
Following on from this, semiconductors accompanied the birth of the AC-DC (alternating current – direct current) conversion device, the rectifier, in 1874.
Two patents were filed in the 20s and 30s for devices that would have been transistors if they had ever reached past the theoretical stage. In 1925 Julius Lilienfeld of Austria-Hungary filed a patent, but did not end up releasing any papers regarding his research on the field-effect transistor, and so his discoveries were ignored.
Again, in 1934 German physicist Oskar Heil’s patent was on a device that, by applying an electrical field, could control the current in a circuit. With only theoretical ideas, this also did not become the first field effect transistor.
The invention of transistors
The official invention of a working transistor was in 1947, and the device was announced a year later in 1948. The inventors were three physicists working at Bell Telephone Laboratories in New Jersey, USA. William Shockley, John Bardeen and Walter Brattain were part of a semiconductor research subgroup working out of the labs.
One of the first attempts they made at a transistor was Shockley’s semiconductor triode, which was made up of three electrodes, an emitter, a collector and a large low-resistance contact placed on a block of germanium. However, the semiconductor surface trapped electrons, which blocked the main channel from the effect of the external field.
Despite this initial idea not working out, the issue was solved in 1946. After spending some time looking into three-layer structures featuring a reversed and forward-biased junction, they returned to their project on field-effect devices in a year later in 1947. At the end of that year, they found that with two very close contact junctions, with one forward biased and one reverse biased, there would be a slight gain.
The first working transistor featured a strip of gold over a triangle of plastic, finely cut with a razor at the tip to create two contact points with a hair’s breadth between them and placed on top of a block of germanium.
The device was announced in June of 1948 as the transistor – a mix of the words ‘transconductance’, ‘transfer’ and ‘varistor’.
The French connection
At the same time over the water in France, two German physicists working for Compagnie des Freins et Signaux were at a similar stage in the development of a point contact device, which they went on to call the ‘transistron’ when it was released.
Herbert Mataré and Heinrich Welker released the transistron a few months after the Bell Labs transistor was announced but was engineered completely without influence by their American counterpart due to the secrecy around the Bell project.
Where we are now
The first germanium transistors were used in computers as a replacement for their predecessor vacuum tubes, and transistor car radios were produced all within only six years of its invention.
The first transistor was made with germanium, but since the material can’t withstand heats of more than 180˚F (82.2˚C), in 1954 Bell Labs switched to silicon. Later that year Texas Instruments began mass-producing silicon transistors.
First silicon transistor made in 1954 by Bell Labs, then Texas Instruments made first commercial mass produced silicon transistor the same year. Six years later in 1960 the first in the direct bloodline of modern transistors was made, again by Bell Labs – the metal-oxide-semiconductor field-effect Transistor (MOSFET).
Between then and now, most transistor technology has been based on the MOSFET, with the size shrinking from 40 micrometres when they were first invented, to the current average being about 14 nanometres.
The latest in transistor technology is called the RibbonFET. The technology was announced by Intel in 2021, and is a transistor whose gate surrounds the channel. The tech is due to come into use in 2024 when Intel change from nanometres to, the even smaller measuring unit, Angstrom.
There is also other tech that is being developed as the years march on, including research into the use of 2D materials like graphene.
If you’re looking for electronic components, Cyclops are here to help. Contact us at firstname.lastname@example.org to order hard-to-find or obsolete electronic components. You can also use the rapid enquiry form on our website https://www.cyclops-electronics.com/
02 March 2022
Could Graphene be used in semiconductors?
A new discovery
Graphene was first isolated at the University of Manchester in 2004. Professors Andre Geim and Kostya Novoselov were experimenting on a Friday night (as you do) and found they could create very thin flakes of graphite using sticky tape. When separating these fragments further, they found they could produce flakes that were one atom thick.
Geim and Novoselov were awarded the Nobel Prize in Physics for their ground-breaking experiments in 2010, and since the two had first identified the material since the 60s it had been a long time coming.
Despite its thinness Graphene is extremely strong, estimated to be 200 times stronger than steel
Is silicon outdated?
Semiconductors are inextricably linked to Moore’s Law, which is the principle that the number of transistors on a microchip doubles every year. But that observation Intel co-founder Gordon Moore made in 1965 is now losing speed.
Silicon chips will very soon reach their limit and will be unable to hold any additional transistors, which means that future innovation will require a replacement material. Graphene, with its single-atom thickness, is a contender.
In 2014 hardware company IBM devoted $3 billion to researching replacements for silicon as it believed the material would become obsolete. The company said as chips and transistors get smaller, as small as the current average of 7 nanometers (nm), the integrity of silicon is more at risk.
IBM revealed its new 2nm tech last year, which can hold 50 billion transistors on a single silicon chip, so the material is not going obsolete just yet.
Graphene is nowhere close to being a replacement for silicon, it is still in the development stage and the cost of implementing it into supply chain would be extensive. A lot more research and adjustment is required, and it would have to be introduced step by step to avoid prices skyrocketing and supply chains breaking down.
Graphene is not the only contender to be the replacement for silicon either. Carbon nanotubes are fighting for prominence, and other 2D materials like molybdenum disulfide and tungsten disulfide are also vying for the position.
Another disadvantage of Graphene is that there is no bandgap, which means the semiconductor can’t be switched off. The possibly jagged edges of the material could also pierce the cell membranes which may disrupt functions.
Thanks to its 2D properties Graphene is also being studied for its potential uses in other areas. In relation to semiconductors there has been research from Korea on the uses of graphene as a filtration device for semiconductor wastewater. The oxide-based nanofiltration membranes could remove ammonium from the wastewater created by semiconductor production so it can then be recycled. As a wider application of this Graphene could be used as a filtration device for water or to remove gas from a gas-liquid mixture.
Graphene is also being researched for its uses in the biomedical field, which include being a platform for drug delivery, bone tissue engineering, and ultrasensitive biosensors to detect nucleic acids. Graphene has other sensor-based uses, because the sensors can be made in micrometre-size they could be made to detect events on a molecular level, and could be of use in agriculture and smart farming.
There is a possibility Graphene could be combined with paint to weather-proof or rust-proof vehicles and houses, and to coat sports equipment. It also could have potential within the energy field for extending the lifespan of lithium-ion batteries.
When can we expect change?
Consultation company McKinsey estimated there would be three phases to the implementation of Graphene, none of which have begun just yet. Phase one would be to use Graphene as an ‘enhancer’ of existing technology, and will simply improve other devices by extending the lifespan or improving the conduction. This phase is estimated to last for ten years, after which phase two will begin. In this step graphene will become a replacement for silicon and will be the next step in the improvement of semiconductors and electronics. After 25 years we can expect the next step in graphene applications, things we can only dream of now.
In the meantime, people will still be using silicon-based semiconductors for quite a while. If you’re on the lookout for chips, or any other day-to-day or obsolete electronic components, contact Cyclops today at email@example.com, or use the rapid enquiry form on our website.
16 December 2020
The multimodal transistor (MMT) is a new design philosophy for electronics
Researchers from the University of Surrey and University of Rennes have developed a technology called the multimodal transistor (MMT), which could revolutionise electronics by simplifying circuits and increasing design freedom.
The multimodal transistor is a thin-film transistor that performs the same job as more complex circuits. The MMT sandwiches metals, insulators and semiconductors together in a package that’s considerably thinner than a normal circuit.
However, the key breakthrough with the MMT is its immunity to parasitic effects (unwanted oscillations). The MMT allows consistent, repeatable signals, increasing a transistor’s performance. This is necessary for precision circuits to function as intended and is especially useful for next-gen tech like AI and robotics.
How it works
In the image below, we can see the design of the MMT. CG1 provides the means to control the quantity of charge, while CG2 is the channel control gate. CG1 controls the current level and CG2 controls the on/off state.
This is a massive shift in transistor design because it enables far greater engineering freedom. It is a simple and elegant design, yet it is so useful. It has numerous applications in analogue computation and hardware learning.
MOSFET transistors are one of the building blocks of modern electronics, but they are non-linear and inefficient.
In a conventional circuit, gate electrodes are used to control a transistor’s ability to pass current. The MMT works differently. Instead of using gate electrodes, it controls on/off switching independently from the amount of current that passes through. This allows the MMT to operate at a higher speed with a linear dependence between input and output. This is useful for digital-to-analogue conversion.
The breakthrough in all its glory
The MMT transforms the humble transistor into a linear device that delivers a linear dependence between input and output. It separates charge injection from conduction, a new design that achieves independent current on/off switching.
There is a profound increase in switching speed as a result of this technology, enabling engineers to develop faster electronics. Researchers estimate that the switching speed is as much as 10 times faster. Also, fewer transistors are needed, increasing the yield rate and reducing the cost to manufacture the circuit.
Just how revolutionary the MMT will be remains to be seen. After all, this is a technology without commercialisation. It could find its way into the electronics we use on a daily basis, like our phones. The potential is for the MMT to be printable, allowing for mass production and integration into billions of electrical devices.
With devices getting smarter and digital transformation advancing at a rapid rate, the electronics industry is booming. Semiconductor foundries are at peek capacity and more electrical devices are being sold than ever. The MMT is a unique solution to a problem, and it could make manufacturing electronics cheaper.
With this, comes a great opportunity for the MMT to replace MOSFET transistors. We can think of few other design philosophies with such wicked potential.
Enter Electronic Component part number below.