We all know the mantra of electronics: faster, smaller, cheaper. Ever since Gordon Moore at Intel recognized the correlation between device density and time, we, as an industry, have been obsessed with cramming as much electronics into as small a space as possible. The obsession with device density has enabled some of the greatest technological achievements of humanity. Yet, there is no one rule to govern all of electronics, no one device trend that satisfies all needs. There are still a great many designs that can don’t have the strict space constraints that others have. There is freedom there, freedom to explore other avenues with benefits that would have to be left behind when having to fit within a very small box. It is not an insignificant portion of the market, it is far more than first-year engineering students beginning to learn about circuits and tinkering with a small bag filled with resistors, capacitors, and inductors.
We recognize that here at KEMET—the demand for high-quality, precision leaded components is still strong and we continue to serve that market. Part of what has enabled our longevity over the past 100 years is the leaded components that some of our competitors have forgotten about or outright chosen to ignore. Our Aximax and Goldmax lines of leaded ceramic capacitors still have a place at KEMET and within the market.
Living Without a PCB
Most components end up spending their entire operational lives mounted onto a PCB. Most? So, what about those that don’t end up getting mounted on a PCB? There are many occasions where space constraints are so tight that there is no space for a PCB. Many electrical motors have capacitors attached to the leads of the carbon brushes. Those are not there for show, they are there to absorb the commutation noise that comes from the inductive spikes, which occur because of the rapid connecting and disconnecting between the commutator bars of the rotor. Without those capacitors, the amount of electrical noise and interference created by electrical motors would be significant.
Have you ever used and old electric drill around a radio? When you pull that trigger, the radio goes from your favorite music station to static. The shift happens because the old drill does not have capacitors to absorb the electrical commutation noise. The resulting electromagnetic interference overpowers the radio signal. Losing your favorite song for a few seconds while doing some drilling is not a major loss, but the same could happen to your WiFi signal, Bluetooth signal, or cellular signal as the interference may reach those bands as well.
As cars become more and more connected over RF, all the various motors that power electronics, such as wipers, seats, windows, pumps, and powertrain, may use capacitors to absorb those inductive voltage spikes that can wreak havoc on other electronics, if left unchecked. The future of transportation is autonomous and those self-driving cars that will soon dominate our roads will be in constant communication with one another and with infrastructure. Mission critical communication systems need to operate in real time with no latency. The noise generated by electric motors will need to be mitigated such as to keep those critical lines of communication clear and noise free.
Standing Up to Harsh Environments
Not all electronics live their lives in static, air-conditioned environments or held in shatter-proof cases. Some electrical systems, such as those in automotive and industrial applications, can consist of extreme temperature, vibration, and humidity. MLCCs are rigid bodies of ceramic material that are sintered together in a very hard, monolithic structure. But many times, hard also equals brittle. The most common failure mode of MLCCs is cracking due to flexing of the PCB. Similar to mechanical vibrations due to the piezoelectric effect being decoupled from the board using leaded components, the leaded connections can also help mitigate the mechanical stresses that can travel to the ceramic body and cause cracking.
Handling the Piezoelectric Effect
No, leaded components are not a thing of the past. They still play a role in many electronic systems because of some of their benefits. When using ceramic capacitors, it is common to hear some low-level buzzing or hum when used in switching applications. The hum occurs because of something called the piezoelectric effect. Without getting too deep into the physics of it, the piezoelectric effect is the phenomenon that converts electrical energy in to mechanical energy. In the case of electronics, the effect can sometimes manifest itself as a low-grade hum when the electrical energy that was converted to mechanical energy causes MLCCs to vibrate. The vibrations can sometimes hit the resonant frequency of the PCB and create audible noise and cause the hum. Many low-cost electronics do not take steps to account for the microphonic noise that comes from the piezoelectric effect. There are many ways to mitigate this effect. One of the easiest ways is to decouple the ceramic body from the PCB such as using a lead frame. Using leaded components is another way to mitigate the vibrations that arise from the piezoelectric effect because the mechanical vibrations are decoupled from the PCB.
Leaded Components Still Have a Home At KEMET