Have you ever heard of electrostatic discharge damage? ESD is something that can disrupt SMT assembly, and disrupt the process itself, or lead to failure of particular components of the device you are building.
It is essential to learn how to put ESD under control, but that won’t be easy. Please take a look at our guide, and find out everything when it comes to ESD protection!
1、Electrostatic Discharge (ESD) – Basic Overview
If you want to defeat the enemy, you should get to know it first. That is why we will talk about electrostatic discharge, as that is the best way to learn more about it.
ESD happens if a static charge transfers from one object or surface to another, with the condition that the second object doesn’t have identical electrostatic characteristics.
If you detect ESD, it will happen either because of contact between two surfaces or materials or because the electric field had a breakdown.
That is important because electrostatic discharge is capable of endangering components’ performance and causing their failure. We will agree that it is not something that should when you are in the process of SMT assembly, which is why we will discuss how to stop ESD later.
Image 1: Artificially created electric discharge
2、Three Ways of Generating ESD
Take a look at three ways that can generate ESD:
• Friction – it is the contact that happens between two objects or surfaces. After you create contact and separate them again, you might notice electrostatic appearing. The simplest example of this is your clothes. You’ve surely felt static electricity when you touched your clothes at least once in your life. The problem with electrostatic in SMT assembly is that it can compromise the device's performance and its components.
• Conduction – if the parts of your device have pins and lead made of metal, they have the potential to conduct ESD. That means if they find themselves between a component and an object (body, surface). It will transfer electrostatic.
• Induction – some surfaces and objects have huge energy that might touch the electronic parts of your device. That will cause your parts to produce electrostatic themselves.
We presented three ways, but it all comes down to movement being what leads to static electricity and the potential damage.
Image 2: Electrostatic discharge illustration
3、ESD Features and Characteristics
Do you know the most dangerous feature of static electricity during SMT assembly, and what can lead to the biggest damage? It is that humans might not recognize ESD at all.
You see, the electrostatic discharge needs to be of a certain volume for humans to identify it. Unfortunately, even levels lower than the ones we can notice can endanger an electronic device's components.
ESD of low power is more than enough to cause huge damage to the product you are assembling. That low power cannot harm people, and it is so low that they don’t even notice the damage to the components.
As for other features, it is vital to note that the ESD starts and ends quickly. It doesn’t take more than a millisecond for the electrostatic discharge to damage the components.
It is also important to note that humidity may contribute to ESD, which is why you should consider putting it under control.
Image 3: Warning about a device sensitive to static electricity
4、ESD Damage – Is It an Important Concern
You have two types of damage that ESD can cause:
• Hard damage – it causes a direct failure or noticeable damage to a component or device.
• Soft damage – you might not notice this type of damage unless you conduct a detailed inspection. However, it may affect how the part performs over time, and it may limit its lifespan.
It is natural that the components will perform at their highest first, but decrease their performance level later. ESD damage can accelerate the time needed for that decrease, and that is a real danger.
The statistics are somewhat encouraging – the experts estimate that every tenth damage caused by ESD causes a direct failure. But if you identify why electronic devices failed, ESD will be the cause in 33% of the cases. In other words, every third device will stop functioning because of electrostatic damage.
That is why preventing ESD damage throughout the entire SMT assembly process is a vital concern for all manufacturers and users.
The PCB industry, for example, has made huge progress regarding reducing the size and weight of the board. The manufacturers also managed to keep the highest level of reliability while securing a lightweight product. Thanks to that, PCBs manages to be a perfect fit for most assemblies. But ESD damage is a real concern for them, too. That is why the manufacturers need to apply measures to prevent potential damage during the assembly process.
Image 4: ESD sparks over electronic components
5、How to Protect SMT Assembly from ESD Damage
ESD is a sneaky thing, and it can cause damage under the radar, and without you even noticing it. So, what else can you do? The best idea is to focus all your efforts on preventing ESD damage.
That won’t be easy because there are steps to take throughout the entire SMT assembly process. The key lies in identifying the most sensitive areas and keeping electrostatic from forming there. In other words, you go to the source of static electricity and prevent it.
Keep in mind that you might not be able to stop all ESDs out there. However, as long as you keep things under control, there won’t be any noticeable damage.
Start with equipping the entire area where you assemble the product with anti-static features. It doesn’t matter if it is a small private workshop or a big factory. The idea is the same – eliminate as much static as possible, and minimize pleasant conditions for creating static.
Experienced manufacturers will place anti-static PVC floors and paints all over the area. It is also vital to place warnings that you can't enter unless dressed properly. Additionally, you want to ensure the floor has no scratches and clean any dust regularly. If you deal with sharp materials, be careful, and put them anywhere but on the floor.
If you have the option, use materials for components and equipment that are static-free. That will not always be possible, which is why you should keep the objects with a high electrostatic potential away from the SMT assembly line.
An excellent trick that you can use involves getting an item that has a high ESD potential. If you connect it to your components, you will ensure that it handles all the discharge hits instead of the device itself.
Finally, keep in mind keeping humidity under control as that is another electrostatic source that you can’t neglect.
Image 5: An ESD protected factory environment
6、How Human Body Protection Can Benefit for Preventing ESD Damage
Have you completed protecting the facility? In that case, you can move on to protecting yourself and the rest of the staff. Ensuring that your body can't transfer and generate static electricity will prevent ESD damage on electronic devices. You've surely seen anti-static clothes in movies. The clothing pieces include a special suit, shoes, hats, gloves, etc.
You should wear all these before you get into the area where you do the SMT assembly, and don’t even think about getting near the assembly line without protection. A warning at the area's entrance can be a great reminder that you shouldn’t enter an anti-static space without proper equipment.
If you want, think of your body as a grounding circuit that can stop static electricity from accumulating. Although it can help minimize ESD damage, it is vital to note that grounding is not smart for insulating materials. Ion neutralization can be the right solution in that case.
Image 6: anti-static wrist strap and clothes
7、Protecting Circuits from ESD During Storage and Transport
If you manage to push through the entire SMT assembly without compromising ESD damage components, we congratulate you. However, you still have to ensure that ESD won’t harm the components during storage and transport. That is where ESD bags can play a huge role as they were specially designed to keep the components inside safe from electrostatic discharge damage.
It may seem like a lot to handle all these factors yourself, which is why you should consider hiring a professional to assemble your components. OurPCB is a company that has been in the industry of designing printed circuit boards for years.
The manufacturer has state-of-the-art equipment, as well as knowledgeable and experienced staff. That ensures that they can handle the entire PCB process flawlessly and ensure your board's maximum reliability and performance. If you have any printed circuit board requirements, please contact the company to ask for advice and place your order.
Image 7: anti-static bag with a product inside
Even if you have neglected it so far, we hope you realized how damaging electronic discharge could be to your device's components. It is vital to take the necessary steps to protect the product and its parts from ESD damage during the SMT assembly.
That won’t be an easy job as it will take a lot of time and effort. You want to eliminate or minimize ESD from the moment you start assembling the product until the actual storage and transport. Since that can be too demanding, you can consider hiring a professional to design components for you in a static-free environment.