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.

Why HASL and LFH are Concerned as a Hassle?

Hot air solder leveling, also known as HASL, has always been the major part of PCB surface finishes. As an excellent solderable finish for printed circuit boards, it has kept this surface finish alive in the market since late 80s. Given that PCBs are in everything from appliances to toys, it was almost instinct to find an alternative. Exposure of lead to children and overall health in general being a concern, getting lead out of products was the focal point of the electronic manufacturer.

It is obvious that lead may never be totally gone from all products, then the lead free version (LFH) existed. It became the most practice at surface finish next to immersion gold early on. So, why is lead free HASL still considered a hassle? 

The chemistry makeup of LFH has changed over the years as well as the applications. Vertical or horizontal applications both initially had the same issue as HASL, a pooling, non-flat finish with a somewhat foggy appearance in areas of the PCB.

Combinations of the LFH gave the finish a bad review. The combination of tin, silver, and copper alloy originally had poor results at the processing level, leaving behind a bumpy uneven coat that was dull and unattractive as well as having a poor performance in assembly. Removing the silver, changing the tin-copper, and tweaking the manufacturing process has allowed for a better smoother surface coating than originally found.