How does ESD Affect Your PCB Board?

Electrostatic discharge (ESD) occurs when two objects with different charges get close enough, or charged enough, to break down the dielectric between them. 

Any PCB may be subject to an ESD if it’s touched or comes close enough to people, packaging, cables, furry pets, or any other object that might contain an opposite charge. When they do touch, that voltage discharges and creates a comparatively massive voltage spike. As the voltage spike dissipates, the discharge current generates electromagnetic fields across the PCB. The goal of ESD protection is to minimize any impact or effects from the discharge.

In particular, many modern chipsets are made using such small lithography features that they have little or no tolerance for high voltage, even direct current values above their operating voltage of 3.3V. The result of an ESD event directly reaching one of these components is usually disastrous, completely ruining the integrated circuit.Nearly every element of your PCB design (traces, routing, layers, component placement, and spacing) can affect the ESD protection on your board. That means you need to consider ESD early in your design process; otherwise, you’re likely to require major PCB redesign to fix routing and component placement issues.

Use A Chassis Ground

Similar to grounding yourself and a computer tower case before you start pulling things out, you can ground the external casing of your PCB board. By allowing your board and chassis to share a ground, you can improve the grounding of the entire system. One of the easiest ways to implement a chassis grounding is to include a “chassis screw” that connects the ground plane to the chassis. However, you need to make sure you’re using adequate standoffs so other components aren’t crushed or shorted to the casing when the PCB is screwed in. 

Additionally, grounding with a chassis screw makes ESD protection circuits more effective when you’re using transient voltage suppression at inputs. Remember, you’ll want to separate the chassis ground from the digital and analog ground by using inductive components. That way, a discharge into ground won’t accidentally be shared with all your other components.

If you are designing high-speed circuits, you know that they are always more difficult to optimize for performance. This is especially true if you’re routing across multiple ground planes, like a chassis and a PCB layer. The best case scenario is that you can connect the chassis ground directly to an earth ground. If that’s not an option, you should keep all of the ground planes tightly coupled to each other. That will help to minimize any “ground shifts” around key components.

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.

PCB Board

A printed circuit board, or PCB Board, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. When the board has only copper tracks and features, and no circuit elements such as capacitors, resistors or active devices have been manufactured into the actual substrate of the board, it is more correctly referred to as printed wiring board (PWB) or etched wiring board. Use of the term PWB or printed wiring board although more accurate and distinct from what would be known as a true printed circuit board, has generally fallen by the wayside for many people as the distinction between circuit and wiring has become blurred.