An electronic product’s PCBA is its heart and nerve center rolled into one. It is the circuit board that contains crucial components that allow the device to think, move, operate, and function as normal. So, it stands to reason that it needs to be protected to maintain product reliability.
It’s possible to physically protect the PCB (or PCBA once it has components added to it) and also design products to naturally be more durable and reliable which will, in turn, protect the internal components…let’s explore them here.
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What is the PCB and why is it so important?
The PCB is a printed circuit board that includes many of an electronic product’s components that drive its functionality, such as its processor or WiFi functionality. When components are attached to it (soldered on) it is commonly referred to as a PCBA or Printed Circuit Board Assembly. Without the PCB an electronic product almost certainly won’t work, therefore it is a critical part of the product that must be protected appropriately depending on the product type, how customers are expected to use it, and the environments it is expected to be in. (01:45)
How and why do we protect the PCBA?
Different products have different needs, such as being waterproof or dustproof. Depending on what the product will face during its lifetime, you will either directly apply some kind of protection to the PCB itself or put in place measures to prevent any water, dust, or contamination from getting to it which could be sealing the product, using a special type of enclosure, or more. (03:04)
Introducing conformal coating.
This is a thin film applied to the PCB which provides a physical barrier that protects against water, dust, temperature changes, and more, which makes a PCBA more reliable because it’s less likely to suffer from shorts, corrosion, and other negative impacts from external elements getting in contact with it. There are options for the importer to choose from, some conformal coatings dry quickly and are hard, whereas others are more like a flexible silicone-type substance. (04:40)
Other PCBA protection options.
To ensure a product is reliable, product designers can take a DFM or DFR approach where they design the product from the early stages of new product development to be more reliable and easier to manufacture, putting in place relevant protective solutions if deemed necessary. A good example is a military laptop which is built into a rugged case that protects it against even heavy damage.
As well as conformal coatings, you may use other methods to protect the PCBA and product in general.
- Design a protective enclosure: For example, for a product that needs to resist impacts, designing a hard and rugged or perhaps a softer impact-resistant enclosure makes sense. This protects the product as a whole, including the PCB inside it.
- Source more reliable components: Designers don’t always think about using rugged or more reliable components which are individually sealed, made to be waterproof, or resistant to electrical shorts, etc, in the product design, but by including components like this from the start you can improve the device’s reliability in a fairly simple way.
- Seal the product: Instead of sealing the PCB, you can use a gasket to seal the enclosure against dust, moisture, etc, or use a type of silicone putty along the join to provide the same kind of seal. These methods can work but are not as effective as conformal coating for PCBs. (08:51)
The process of protecting a product from the inside out.
Let’s say you select components that are designed and tested to be reliable. The weak link might be their solder connection to the PCB itself. In this case, you need to design the product to be hardened from the inside out. That means selecting reliable components and PCB type for the product (some products can benefit from a firmer PCB whereas it can be more flexible in others, but if used incorrectly it could flex and the components might come off which is the popcorn effect). Also use production processes that promote reliability, such as using a pick and place process that is accurate and the correct type of solder at the right temperature to give a solid connection. Using a conformal coating to bond everything together firmly. Using a rugged enclosure that might need to be designed to be durable is a last step. (14:14)
The costs of protecting PCBs.
Conformal coating costs approximately 2-10 US cents per square inch, although prices are probably lower for higher volumes.
Gasketing is probably 50% cheaper, but it is also less effective at protecting the PCB and internals of the product.
Investing into designing a more reliable and durable product from the start is probably the most expensive option, but also the most effective as you are able to design the product to resist all kinds of environmental stresses rather than putting in place a measure to combat just one. But is this extra development and BOM cost less than the cost of unreliable products, product returns from the field, and angry customers? Almost certainly. (18:42)
The coating process.
After the PCBA is assembled the conformal coating may be sprayed on, or the PCBA may be dipped into the coating medium. Then it is cured by air drying, being in a heated environment, or even by using UV. (23:44)