Battery Internal Resistance

In this article, we will go over the battery internal resistance. All batteries have internal resistance to some degree because the elements it composed of are not 100% perfect conductors. Though the internal resistance may be low, always around 0.1Ω  for an AA alkaline battery, and about 1Ω  to 2Ω  for a 9-volt alkaline battery, it can cause a noticeable drop in output voltage if a low-resistance load is attached to it.

This is easily understood if you still remember how voltage division works. The larger the resistance is, the more voltage gets allocated to that component. If a component has a very large impedance, that component will get most of the voltage, which comes from the battery, and vice versa. You should know that voltage gets allocated according to impedance values, so the impedance of the output device and the battery will always be divided up between each other.

Batteries with large internal resistance show poor performance in supplying high current pulses. This is because current is decreased with higher resistance. So the higher the internal resistance, the lower the current output ability. That’s why low internal resistance batteries are much better at supplying high current pulses.

Battery Eliminator

A battery eliminator is a device providing power to an electronic circuit. It can be any number of devices, such as a direct current power supply, etc. to power an electronic device. But why we use a battery eliminator instead of using batteries? 

The reason is because it can be a substitute if you do not have batteries, or you do not have the correct type, or if all of your batteries have run out of. Being that most electronic circuits run off of direct current power, you can use any direct current power source to power the electronic device, as long as you use the voltage it needs. So if all your batteries have died or you just currently don't have the right type, you can still power the device, using any device which can provide the direct current voltage which your device needs. Battery eliminators can do this.

Another reason is that if you're designing a circuit and you're trying to figure out the right voltage needed, constantly changing and swapping out batteries can be very tedious. With a battery eliminator, you can simply change direct current voltage just by adjusting a knob, and all you have to do is to rotate a switch.

Circuit Breaker Panels

If you are not familiar with the circuit breaker panels, this article posted by EPCB may be useful for you. Nowadays, circuit breaker panels have replaced the outdated fuse panels because we are running more and more electrical products. 

Some circuit breakers can control 120-volt circuits, while others are able to control 240-volt circuitry which can be used for electric dryers, electric ranges, electric water heaters, etc. Among the different circuit breakers, a main circuit breaker, usually a 100-amp or 200-amp main breaker, is the most important one with whom the whole electrical panel is powered. 

People are used to comparing a fuse with a circuit breaker, both are helpful components. But unlike a blown fuse, a circuit breaker is better for it can be reset after it trips, which means you don’t have to replace them like you do with fuses. You’d better have circuit trips and be able to reset it before finding it completely becomes a defective circuit breaker. The circuit breakers are so useful that they are widely used to power our home.

HDI PCBs

Compare to standard rigid PCB, HDI PCBs or high density interconnect PCBs require a much higher wiring and pad connection density. They are featured by finer trace and spacing, smaller capture pads, and micro-sized vias.

HDI PCBs are widely used for cell phone, tablet computer, digital camera, GPS and other different area. That’s because the market demand for lightweight and thinner PCBs which can handle high-speed signals with reduced signal loss has steadily increased, and compared to other PCBs, HDI can meet these requirements better.

Except the advantages of lightweight and steady high-speed signal, HDI PCBs also have the strengths in the following aspects. They are lower cost, better reliability, enhanced wiring density, improved design efficiency and thermal properties, advanced packaging technology, better electrical performance and signal correctness, improved frequency interference radio, electromagnetic interference and electrostatic discharge.

Advantages of Metal Core PCB

Metal core PCBs have been used frequently in electronic products, especially for LED products. In this article, EPCB would like to outline its advantages. 

Thermal Conductivity: For many double-sided PCBs or multilayer PCBs with high density and power, heat dissipation is really a big challenge, because high temperature can make electronic components fail to work. The normal PCB raw material we used frequently now, such as FR-4, has poor thermal conductivity and inter-layer insulation. So we need to use metal core PCB instead, which has an excellent thermal conductivity. 

Thermal Expansibility: There is a physical principle says objects will expand with heat and contract with cold. The CTE or coefficient of thermal expansion is different with different objects. Metal core PCB can effectively deal with the heat and the problems of thermal expansion and contraction, improve the durability and reliability of equipment.

Scale Stable: Compare with FR-4 PCB, the scale of metal core PCB is much more stable. For example, aluminum PCB is heated from 30℃ to 140~150℃, but its scale only changes from 2.5%~3%. So the metal PCB is more suitable to work in the condition of high temperature.

PCB Panelization

Some PCB board is really small with irregular outlines, bringing much trouble to PCB manufacturer process as single pcs. To improve fabrication efficiency, PCB manufacturers usually require panelized PCBs, which not only can shorten PCB manufacturing lead time, but is easy to control quality and count PCB quantity before shipment. In this article, EPCB will outline four types of PCB panelization, and hope it really useful for you.

The most common way is panelization with break-away but without spacing between each single pcs. Most customers do not have any special requirements on PCB outline, so V-CUT is often used to depanelize the PCB into single pcs. 

Compared to type 1, this panel board type has both break-away and spacing between each single pcs. If customers have special requirements on PCB outline and board edge, we will use the profile of routing, thus, it requires spacing between each single board, generally the spacing is within 1.5~2mm. 

As to a panelization without break-away, it is convenient for shipment, but not helpful for follow-up process, but this kind of panelization will save cost for board edge, so the wholr cost can be reduced to some extent. 

Finally is a panelization with stamp holes, PCB manufacturers could use stamp hole connection to control and reduce burs, so the stamp holes can be used to replace V-CUT.

LED Aluminum PCB

LED aluminum PCB is made up of the circuit layer, thermal insulation layer and metal core layer. 

Circuit layer require great current-carrying capacity, thus should use thicker copper foil and generally the thickness is from 35um to 280um. Thermal insulation layer is the core technology of aluminum PCB, and usually consists of special ceramics and fill special polymers with small thermal resistance, good viscoelasticity. It also has thermal aging ability, and can withstand mechanical and thermal stress. 

As to metal core layer, it is the support part of aluminum PCB, which require high heat conductivity. Basically the aluminum base is suitable for drilling, punching, shearing, cutting and other regular mechanical processing. Surface treatment include: gold plated, HASL, OSP, Immersion gold, lead-free ROHS process, etc.

Features of aluminum PCB are as follows: thin insulation layer, low thermal resistance, good heat dissipation, high mechanical strength. Its standard thickness is 0.8mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm, 2.5mm or 3.0 mm. Its copper foil thickness is 1.8um, 35um, 70um, 105um, or 140um.