1. PCB manufacturers here claim that their products can reduce the water ingress rate, but they do not state that this nano-coating can achieve waterproof levels. Therefore, it is accurate to say that this nano-coating can inhibit moisture but cannot completely prevent water ingress.
2. In fact, if you have a friend who drives, you may know of a water-repellent product that, when sprayed on the front windshield, effectively minimizes water droplet adhesion and the problem of residue on the glass. This type of water repellent is a form of nano-coating material.
3. Many people may not realize that humid environments can be quite detrimental to electronic products. For instance, moisture is a major contributor to CAF (Conductive Anodic Filament) micro-short circuits. If we can significantly enhance the moisture resistance of the circuit board, it could reduce the occurrence of CAF or delay its onset.
4. Additionally, many PCB products often experience leakage current or even circuit board corrosion due to residual flux from the soldering process. By isolating moisture, these products can also achieve a longer lifespan.
Another advantage of using this type of “nano coating” is that if a customer accidentally spills carbonated beverages or liquids on the product, particularly with the serial port connected, some liquid may inevitably remain inside the device even after external cleaning. Over time, this trapped liquid can corrode circuit boards and components.
When evaluating the use of Conformal Coating to address these reliability issues, it’s important to note that applying Conformal Coating can be quite time-consuming and labor-intensive. Paint stains may occur on components or areas needing contact, such as connectors, which can lead to poor connectivity after assembly. This rework can be cumbersome, and some issues may still be intermittent, which is frustrating.
Interestingly, this PCB manufacturer claims that their nano-coating does not require any mask protection for parts or contact points during spraying, and it can be applied after the entire machine is assembled. This means that after the product is fully built, it can proceed directly to gluing.
This might sound unusual, but the manufacturer recommends coating the entire machine rather than individual circuit boards. Their nano-coating employs PECVD (Pulse Enhanced Chemical Vaporized Deposition) and utilizes vacuum equipment, allowing nano-sized particles to permeate the tiny gaps in the product and adhere to most internal corners. Furthermore, because the coating gap is smaller than water molecules, it effectively isolates moisture’s impact on electronic devices. Additionally, with a thickness of only about 5-50nm, spring parts (like connectors) can easily rub off the coating for electrical contact, eliminating the need for masks.
The reason PCB manufacturers assert their products are moisture-proof yet not fully resistant to water ingress is that the nano-coating can adhere to any part of the product, sealing small gaps. However, if a foreign object disrupts the coating at an interface slot, the moisture protection can be compromised. The coating remains effective in areas without foreign object interference, providing moisture protection.
**Restrictions and Potential Issues with Nano Coating**
▪ For products not requiring friction, such as silicone zebra stripes, further testing is needed to confirm if they can be sprayed on the circuit board before assembly, as there’s no data from the manufacturer to support this.
▪ If the nano-coating is applied to the PCBA circuit board before assembling the complete machine, care must be taken to position the circuit board correctly; otherwise, there’s a risk that the coating may wear off where fingers make contact.
▪ During nano-coating application, a vacuum is used, and specific components require extra caution. For instance, items like electrolytic capacitors and batteries, which contain chemical liquids, could face risks of leakage or explosion if internal and external pressures differ.
▪ When processing this nano-coating, specialized spraying equipment from the PCB manufacturer must be used. For small quantities, the product needs to be sent to the manufacturer for processing. For larger production runs, discussions regarding equipment rental or on-site manufacturer assistance can help avoid the logistics of sending products back and forth.
▪ In practical applications, if the product is dropped, the coating in the gaps may crack due to deformation from external forces.
