PCB: The Hidden Treasure

Most printed circuit boards are made from fiberglass or plastic, non-ferrous metal, and other recyclable materials. Gold is one of the most commonly found precious metals in integrated circuit boards, as it is an excellent conductor of electricity and is highly resistant to corrosion.

Additionally, printed circuit boards may also contain other valuable metals – silver, platinum, palladium, copper and nickel – that can be extracted from them and reused to make a variety of new products, including circuit boards.

Certified and credible e-waste recycling companies have emerged these years, they typically use internationally accepted methods of processing PCBs, which means they’re sent to specialized smelters to recover precious metals. So, you can take your electronic waste for safe recycling.

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Track Sizes

There is no recommended standard for track sizes. What track sizes you use mainly depend on the electrical requirements of the design, the routing space and clearance. Every design will have a different set of electrical requirements which can vary between tracks on the board.

All but basic non-critical designs will require a mixture of track sizes. As a general rule though, the wider, the better. That’s because wider tracks have lower DC resistance and therefore higher current capacity, lower inductance, can be easier and cheaper for the manufacturer to etch, and are easier to inspect and rework.

The lower limit of your track width will depend on the fabrication ability of your PCB manufacturer. Typically, figures are 10/10 and 8/8 for basic boards. The IPC standard recommends 4 thou as being a lower limit. The lower the track figure, the greater care the manufacturer has to take when aligning and etching the board, and this will cost you more. 

As a start, you’d better to use 25 thou for signal tracks, 50 thou for power and ground tracks and 10-15 thou for going between IC and component pads. Good design practice is to keep tracks as big as possible and then to change to a thinner track only when required to meet clearance requirements.

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Track Clearances

Electrical clearances are an important requirement for all boards. Too tight a clearance between tracks and pads may lead to hair-line shorts and other etching problems during the manufacturing process. These can be very hard to find once your board is assembled. At least 15 thou is a good clearance limit for basic through-hole design, with 10 thou or 8 thou being used for denser surface mount layout. 

As a rule of thumb, an absolute minimum of 8mm equals to 315 thou spacing should be allowed between 240V tracks and isolated signal tracks. The clearance varies based on whether the tracks are on internal layers and the external surface. They also vary with the operational height of the board above sea level, due to the thinning of the atmosphere at high altitudes. Conformal coating (a non-conductive spray often applied over the tracks to resist moisture, corrosion, etc) also improves these figures for a given clearance. 

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Snap Grid

A major rule of PCB design which always missed by beginners is to lay out your board on a fixed grid. This is called snap grid, as your components and tracks will snap into fixed grid positions. 100 thou is a standard placement grid for very basic through-hole work, while 50 thou is a standard for general tracking work. For even finer work, you may use a 25-thou snap grid or even lower. 

Why is a coarse snap grid so important? That’s because it will keep your components neat and symmetrical. Besides, it makes future editing, dragging, movement and alignment of your tracks, components and blocks of components easier as your layout grows in size and complexity.

Enough PCB layout practice is very crucial for your future. You’re required to start out with a coarse grid like 50 thou and use a progressively finer snap grid if your design becomes tight on space. Drop to 25 thou and 10 thou for finer routing and placement when needed. This will do for 99% of boards. Make sure the finer grid you choose is a nice, this means 50, 25, 20, 10, or 5 thou is a good choice.

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Safety Basics of Electrical Grounding

Safety basics of electrical grounding involve making sure all wires and cords are undamaged, checking that all circuits are performing well and none electrical fittings need to be replaced or repaired. Electrical grounding is the process of stabilizing an electrical current in order to limit the variation and volume of a machine's electrical current. 

When performing any electrical grounding work, workers should be sure to have a strong understanding of the process of grounding and the type of electrical current that is being worked with. Workers should also keep a first aid kit close by in case of injury. Workers should be aware of common symptoms of serious electricity-related injuries. Because of the high risk of electrical shock, it is also wise to only use non-conductive tools or tools with non-conductive handles and grips. Tools like these can absorb limited amounts of electricity and protect the user from serious harm.

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Pads

Pad sizes, shapes and dimensions depend not only on the component you are using but also the manufacturing process used to assemble the board. There is an important parameter known as the pad/hole ratio. It is the ratio of the pad size to the component lead hole size in that pad. As a simple rule of thumb, the pad should be at least 1.8 times the diameter of the hole or at least 0.5mm larger. This is to allow for alignment tolerances on the drill and the artwork on the top and bottom layers.

There are some common practices used when it comes to generic component pads. Pads for leaded components like resistors, capacitors and diodes should be round, with around 70 thou diameter being common. Dual in line (DIL) components like integrated circuits are better suited with oval shaped pads (60 thou high by 90-100 thou wide is common). Most surface mount components use rectangular pads with circular ends and the pads should not be any wider than the component itself. As a general rule, use circular or oval pads unless you need to use rectangular.
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Different Transformer Types

Some different types of transformers are power transformers, potential transformers, audio transformers and output transformers. A transformer transfers electrical energy from one electrical circuit to another without changing its frequency. 

Power transformers are used in electric power transmissions and electrical appliances to convert main voltage to low voltage. Laminated core and toroidal transformers are two power transformer types. Laminated core transformers have an insulated lamination that minimizes eddy current loss in the inner core, while compared to laminated core transformers, toroidal transformers have a lower external field and need less space. 

Potential transformers are used to monitor single-phase and three-phase power line voltages in power metering applications. There are three types of potential transformers: optical, capacitor and electromagnetic transformers. Optical transformers are designed for optical materials. The electromagnetic and capacitor transformers are both designed for higher voltage applications.

Audio transformers are used to carry audio signals in audio circuits. They provide impedance matching between high and low impedance circuits. Audio transformers are commonly used to interconnect professional audio systems components.

Instrument transformers are used to operate instruments from high current circuits or high voltage lines. Two instrument transformers types are current and potential transformers. Current transformers are used with an ammeter to measure current in AC voltages, while potential transformers are used with a voltmeter to measure voltage in AC.
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Necking

Changing your track from large to small and then back to large again is known as necking or necking down. This is often required when you have to go between integrated circuits or component pads. You can have nice big low impedance tracks with enough flexibility to route between tight spots.

In practice, your track width is designed according to the current flowing through it and the maximum temperature rise you are willing to tolerate. Every track will have a certain amount of resistance, so the track will dissipate heat just like a resistor; the wider the track, the lower its resistance. 

The calculations to figure out a required track width based on the current and the maximum temperature rise are a little complex. As a rule of thumb, a 10° Celsius temperature rise in your track is a nice safe limit to design around. In addition, the wider the track, the better.

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Advantages and Disadvantages of Parallel Circuits

The power remains at the same voltage as the voltage of a single power source is the major disadvantage of parallel circuits. Parallel circuits have more than one output device or power source, so electricity has more than one path to flow. Another disadvantage in parallel circuits is that the energy from the source is usually split across the entire circuit. Therefore, there are varying currents flowing in the circuit. As a result, where a constant current is desired throughout, parallel circuits cannot be effectively used. Similarly, the resistance in parallel circuits is much lower. 

Parallel circuits also have many important advantages. For example, the bulbs connected in parallel circuits tend to have brighter light than those connected in series circuits. In addition, when one bulb is turned off, it does not affect the others. So you can easily found parallel circuits used in houses, such as microwaves, refrigerators, heaters and television sets. This system is capable of providing each appliance with the full mains voltage, and a homeowner can turn on one appliance without necessarily turning on another.

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Grid Types

A snap grid and a visible grid are two main types of grids in PCB. The visible grid is an optional on-screen grid of solid or dashed lines, or dots. You can have a snap grid or visible grid set to different units (metric or imperial). Many designers prefer a 100 thou visible grid and rarely vary from that.

An electrical grid is also used in some programs. This grid is not visible but it makes your cursor snap onto the center of electrical objects like tracks and pads. This is extremely useful for manual routing, editing and moving objects.

One last type of grid is called component grid. It works the same as the snap grid but only for component movement. Component grid allows you to align components up to a different grid.

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Dangers of Not Recycling PCBs

That PCB boards are found in all types of electronics is clear, but what’s perhaps not so clear is why there is so much emphasis on recycling them. As mentioned before, PCBs are a treasure of valuable materials that can be recovered and reused through the process of electronic waste recycling.

Actually, the dangers of not recycling e-waste or just sending to landfills always ignored by people, but the dangers are severe than you can imagine. Electronics contain plenty of hazardous substances, so if we just sending them to landfills, they easily get released into the environment and leak into the groundwater which will potentially pollute the water we drink and pose a serious threat to human health.

Electronics recycling is the most effective way to not just prevent pollution and possible ill-health, but also conserve natural resources. When we recycle valuable materials from electronics, we eliminate the need for extracting these elements from the nature. While resource conservation is a direct advantage of recycling electronic waste, cost and energy savings are the indirect benefits.

Learn more about how to tackle e-waste like PCBs, please visit www.epcb.com

4 Ways to Use Microcontrollers

A microcontroller is useful for a lot of things – like building your own music player, robots, or a display for whatever project you have. Some beginners might think it’s difficult to work with a microcontroller, here we would say, it is absolutely wrong. Here are four ways to easily start using a microcontroller:

Development kit: Most manufacturers of microcontrollers offer development kits as an easy way to test their microcontroller. These are usually well documented, but can be a bit pricey.

Breakout board: This is a board usually with a bare minimum of components which needed to get the microcontroller running. A breakout board is usually cheap, but it requires more knowledge about programmers and compilers.

Build your own circuit: You can just buy a microcontroller chip, and make your own circuit with it. It’s cheap, but you have to know how to build your own circuits as well as the knowledge about programmers and compilers.

Arduino: This is a board that is developed to make it easy to use for artists, designers and people with little technical experience from before. You don’t need to know anything about compilers or programmers, and the code is easy to understand.

It’s better for beginners to start out with Arduino, just because it’s so easy to get something cool up and running in no time. If you would rather learn about compilers and programmers right from the start, then try a breakout board is a good idea.
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How to Debug Your Circuit?

Sometimes a little mistake in your printed circuit board will cost you several hours even more to find out. To debug your circuit effectively, here’s the method we recommend to you. Several steps are listed as follows: 

-Print (or draw) your schematic diagram on a piece of paper

-Looks at the schematic diagram first, and then look at your circuit 

-You can start at the positive supply, and make sure what it should be connected to

-You check your circuit and mark yes as a record on a paper for everything that you have confirmed is there 

-Check one by one in a correct sequence, and do this until all the connections are checked

It may take you a little extra time, but it is really helpful, and save more time for you to some extent. 

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How to Adjust the Brightness of an LED

LED is kind of mini light bulb, a small component that creates light. Many beginners are likely to make it as their first works as it is simple. But how to adjust the brightness of an LED may still confuse many beginners, actually, there are two ways to change the brightness of the LED. 

Change the resistor value: To change the brightness by adjusting the resistor value just adding a potentiometer in series with the LED. When you adjust the knob of the resistor, the brightness of the LED will change.

Turn it on and off fast: Another method is to turn the LED on and off fast. Maybe a few hundred times per second. Usually you want to use a microcontroller for this. By adjusting the percentage the LED is on versus off, it will appear to the eye that the brightness changes.
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Breadboard

A breadboard is a board that you can use to connect circuits without soldering. Breadboards are often used to build a simple circuit or to test an idea. When you are learning about circuits, you will come across a lot of little circuits that you want to test. Then the breadboard is really useful.

You can build pretty much any circuit that uses through-hole components on a breadboard – as long as you have enough space on it for all the connections and components. But there are lots of connections in some circuits, and this makes it harder to take control of all the wires going around. At some point you won’t be able to connect such circuits on breadboards. One way is to create your own circuit boards, because it won’t be as expensive and complicated as you thought.

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LEDs and Resistors

LEDs and resistors in series are common in our daily life, but how does it work? Here we explain a problem you may face. 

Suppose you have stumbled upon this confusion about series circuit. That you have two 3V LEDs connected in series to a 12V battery. What will happen then? Because the first LED would have 9V across it and the second one 6V, so you may wonder is it possible to burn them? If you use a resistor, it will lower the available volt for the second LED, but how will you make it work?

Actually, an LED will always try to get its specified voltage across itself. Two 3V LEDs in series, connected to a 12V battery will force a lot of current through the LEDs and they will burn out. When you put a resistor into the circuit, the two LEDs will have 3V across each, and the remaining voltage will be across the resistor. Then you can use Ohm’s law to find the proper resistor for the current you want. For the most common LEDs, you can usually aim for 15-20 mA.

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What is the Right Soldering Temperature?

The right soldering temperature is something that always ignored. But, have you ever confused what is the right soldering temperature in various situations? Our suggestion is that you have to get the solder joint hot enough to melt the solder. Most solder melts around 180 to 190 degrees Celsius equals to 360 to 370 degrees Fahrenheit. So we have to get the solder joint hotter than this.

There are few things that will impact the soldering temperature that you need on your soldering iron. If you have a high effect soldering iron with a large soldering tip, you don’t need that high temperature, maybe 250 degrees Celsius is enough. But if you are using a low effect iron with a small, tiny soldering tip which transfers heat badly, you need a higher temperature like 400 degrees Celsius. If you have a huge solder joint, you will need a higher temperature than if you have tiny, small solder joint.

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Why Do You Need to Tin?

To be honest, you don’t really need to tin. But it can help. For example, you can tin the tip of your soldering iron by first cleaning it with a sponge, then apply a bit of solder to the tip. Or you can tin the pin of a component by heating it with your soldering iron, then melt a bit of solder onto it. The advantage is that it will transfer heat better. So when you tin the tip of your soldering iron, it should make the soldering process a bit simpler. Do it every time your tip needs to be cleaned. Tinning the tip of your soldering iron before you put it down for the day is said to help your tip last longer.

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5 Top Soldering Mistakes

These 5 top mistakes beginners are easily make when soldering. EPCB here explains the reason why it is wrong in simple words. Hope it is useful to you.

1. Removing iron before applying solder: Some people are used to heating the pad and the pin, then removing the solder iron before trying to apply the solder. But this will unfortunately not work well. When you remove to iron, the pad and pin will cool down quickly, so the solder won’t melt.

2. Heating only the pad: This is another common mistake. You may heat the pad, then apply the solder. But since the pin is not heated, the solder will not connect properly to the pin.

3. Cutting pins too short: To make the board look nice and neat, some people often push the component all the way into the hole, then cut the pin so that it doesn’t stick out of the board at all. But this makes it hard to solder the pin, and ends up with some solder covering the hole, but not actually connecting the pin to it.

4. Using too little solder: Some people are afraid of using too much solder, so they apply only a little bit. Though the amount of solder isn’t the most important point, it’s better to apply enough solder to a solder joint so as to make sure it connects properly.

5. Afraid to heat the joint too much: You may worry about heating the board too much, so you try to solder the solder joint in less than a second to keep the circuit board from burning. However, you can damage some components by too much heat from the solder joint, but in the beginning it’s not something to worry about.

Through-Hole Components

Through-hole components are electronic components that have pins that go through the board. And you solder them on the other side of the board. Through-hole components have been used in the electronics industry for many, many years. But they are becoming less and less used. Instead, surface-mount components are taking over instead. The reason for this is that surface mount components take less space and require a simpler soldering process. At least it’s simpler for machines to do it – not humans.

But sometimes, maybe it’s better to use through-hole components instead of surface mount components. For example, if you are making a product that you are planning to mass-produce, then it’s a better idea to use surface mount technology. It will be cheaper in the long run. But if you want to make your first blinking light, then stick to through-hole. As long as you don’t have any strict space or cost requirements, then use through-hole when possible. The reason we promote through-hole over surface mount, is mostly because their easier to solder.

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