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.

Heavy Copper PCB Design Tips

Nowadays, heavy copper PCB (copper thickness >4 oz) has become popular in PCB industry because it is suitable for high-voltage and high-power application, as most PCBs are manufactured just for low-voltage or low-power application with traces generally contain from 0.5 oz to 3 oz copper weight. 

But some PCB designers always get the boards fail the current test, why? Because they sometimes forget a fact that every PCB facility has its process limits and capabilities, even on the same design, so once you choose a manufacturer to take your heavy copper PCBs, you’d better consult them three questions before designing. 

1. Their Min Trace Width

   Trace width is a requirement that all designers pay great attention to ensure that the trace can handle the required current capacity on the project. How much current can a copper circuit safely carry and how much heat rise can your project withstand? They are always determined by the traces on the circuits. Thus, it is important for you to know their min trace width and space which they can make for heavy copper PCB.

2. Material for Heavy Copper PCBs

   For PCB in low-voltage or low-power application, use standard FR-4 or high-temperature FR-4 is enough. But as to those projects with heavy copper PCBs which will be used in high-voltage and high-power application, it is ideal to use high Tg material to make sure your final PCBs can endure higher processing temperature.

3. Their Etching Process on Heavy Copper PCBs

   Standard PCBs, double-sides or multi-layers, are manufactured with a combination of copper etching and plating processes. If the way they etch on heavy copper PCBs is the same with etching on standard board, you’ better ask them the base copper on the material and how to etch and plate the extra copper on the circuits. 

All in all, when designing heavy copper PCBs, more contact with your PCB manufacturer for all technical and manufacturing issues can really help you a lot.

PCB Assembly Process

In this article, EPCB outlines the importance of knowing the PCB assembly process for a  designer or engineer. Five different aspects are considered as follows: 

Inspection: Automatic optical inspection is used by most assembly companies. However, not every company really inspects samples or finished PCBs one by one, some of them just do sample inspection. A short or dry joint is really hard to check by visual, let alone many component packages have connections underneath the component body. So your assembler should check this with some kind of x-ray or specialist visual equipment.

Handling: The way your assembler handles electro static discharge and moisture sensitive components really matters. Though controlling static is often regarded as unnecessary, it is a real risk to components. The same applies to moisture sensitivity, you should be careful about which components are rated as moisture sensitive when designing.

Cleaning: The way a PCB is cleaned can affect components to some extent, so you should pay attention to what kind of cleaning process your assembler uses as standard. With the cleaning process there should be a drying process as well, making sure it’s sufficient to completely dry out the board this is especially needed if using Rogers materials.

Reflow: Generally, it is doesn’t matter what reflow process your assembler uses as standard, however some components can be damaged by vapor phase reflow processes. So have a good command of assembly process knowledge is a must, besides, be familiar with component datasheets is sometimes necessary. 

Understand Circuit Diagrams Better

It is not so easy for beginners to understand circuit diagrams better at the beginning. A little trick in this article will make it easier to understand. We know this sounds a little bit boring, but it’s really important. 

The law says that if you sum all the voltage drops in a circuit – it equals the voltage of your voltage source in the circuit. Suppose you have a 9 volt battery connected to two resistors and a diode in series. If you measure the voltages over each of the components – the sum of them will be 9 volts. You don’t need to memorize the name of this law. Just remember that this is how it is.

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.

How to Choose a Microcontroller

How to choose a suitable microcontroller is really hard, at least if you don’t know what you are doing. But we hope you can feel much easier after reading this article.

There are numerous different microcontrollers. But what is really important for your project? Let’s look at some differences between microcontrollers.

You can find 8-bit, 16-bit and 32-bit microcontrollers. These numbers refer to the size of the databus. In practical terms, a larger databus can do more heavy calculations. The 8-bit microcontroller is the most commonly used by hobbyists. In general, the 8-bit microcontroller has fewer pins, so that it’s easier to solder. And it is usually easier to program too.

Different microcontrollers have different amount of memory, number of input/output pins and peripherals. Peripherals are extra functions added to the microcontroller. The two most common microcontroller-brands for hobbyists are probably AVR from Atmel and PIC from Microchip.

Common Soldering Mistakes

One common soldering job might be to put a connector on something like this. The copper that has been exposed to air for a long time forms an oxide layer on its surface and that oxide layer tends to disrupt the alloying process of soldering. So it’s important to be able to get rid of that oxide layer before you begin soldering.

There are two ways to do that. The first is to mechanically remove it. You can do that by using sand paper to abrade away the oxide, and the other way is to chemically remove it and for that. Begin by adding some rosin, placing it in your vice, and heating it with your iron. You will have a nicely tinned piece of copper when a smoke forms as the flux burns off. 

Now, if you try to do the same process with the oxidized copper, you’re going to run into trouble. As you heat the joint after adding the flux, your solder is still tries to find its way. That copper hasn’t been properly soldered and the reason for that is the oxides that have formed on its surface tend to disrupt that alloying process. So in order to make a better solder joint, what you need to do is to remove an oxide layer.

The Confusing Direction of Current

The direction of the current is a bit confusing. Does the current flow from the positive to the negative terminal of a circuit, or the other way around? Actually, it doesn’t matter. When you need to do calculations, all you need to do is to decide on a direction and make your calculations based on that direction. No matter which direction you chose, the results will be the same.

But what is right? No direction is the absolutely “right” direction. Current can flow both ways, depending on if there are positive or negative charge carriers at work. In metals, we have negative charge carriers, also called electrons. They flow from negative to positive. So, in a normal electric circuit based on metal, electrons will flow from the negative terminal to the positive. But, the conventional way of talking about current direction is from positive to negative.