Leaded VS Leadless Packaging in PCB SMT Assembly
Most components used in mass-fabricated small electronics PCB SMT assemblies come into leadless packages, but can elements of leaded packages be used? Before we discuss, we should explain the term. When referring to leaded and leadless packages, we are referring to whether or not a chip has metal leads (sometimes referred to as legs) that are mounted to circuit boards, not leaded versus leadless in terms of the element lead.
By exploring strengths and weaknesses of leaded and leadless packages, we can learn which are preferable for certain applications.
Advantages of Leaded Packaging
Leaded packages have little legs around a component, which can either go through a circuit board and are soldered on the PCB’s backside (through-hole) or directly to the PCB’s front side (surface mount).
Easy to mount on PCB boards is the most obvious advantage of leaded chip packages. They also make PCBs easier to inspect and repair as broken connections can be seen just with the naked eye.
Cost saving is another benefit, since the contact points on leaded packages are larger, they can use coarse solder paste, which is less expensive.
Advantages of Leadless Packaging
Leadless packages save space by keeping the contact points underneath the component instead of on their perimeter. This extra space is crucial for applications like mobiles, tablets, and wearables, where every millimeter counts.
Another advantage of leadless components is their mechanical strength which means you can separate them from PCB boards easily. This is due to their high contact area to package ratio. Since the pins are on the bottom of the components instead of the perimeter, a larger portion of the component is attached to the PCB by solder. The more surface area on a package that is soldered to a PCB, the more likely it is to remain connected.
Soldering tiny leadless components in garages among PCB hobbyists or students maybe not popular anymore, however, most leadless components these days have some kind of evaluation board. By isolating the elements that make leaded and leadless packages great, we hope to help make mass-production more approachable by keeping costs down.