Many a times engineers come across a situation, where they need to decide if it makes sense to stick to a leaded integrated chip package or consider lead-less component package. Answer to this challenging question is, it depends on the requirement.
If you want to know more about integrated circuit packages, please read this article by SparkFun.
Leadless Component Packages
Let’s talk about lead-less packages first. There are many advantages of using a lead-less package:
- Reduced lead inductance, better electrical conductivity due to reduced lead resistance, low thermal resistance.
- The smaller size ( near chip scale footprint), this results in a thin profile, considerable space saving and less weight, which is very critical for some complex and high-density designs.
- Material handling & placement on PCB is easy w.r.t fine pitch packages like QFP.
- Less prone to bridge defects, when recommended PCB design (pad) and stencils are used.
There are various challenges as well in using a lead-less package, like:
- Manual solder / desolder is complex. This makes rework or repair work very difficult and time-consuming. More stress on PCB while desoldering, which also limits no of repairs possible. Special tools are required.
- Complex PCB design and manufacturing. Example, in case of packages like BGA / LLP / QFN, there is very fine pitch, which requires thin clearances. Also many times they need a number of PCB layers.
- After soldering, special inspection(x-ray) is required to confirm good quality soldering.
- Lead-less package component will face more stress in case of thermal cycling, that’s why they are less reliable than leaded packages. I would suggest reading more about the reliability of lead-less packages if you are using these packages for the first time in a critical project.
Leaded Component Packages
Now, if we talk about leaded packages like QFP, SO, etc. They have various advantages as mentioned below, that’s why some engineers prefer leaded packages in many situations:
- Easy to manually solder and desolder. Repair is relatively easy & less time-consuming.
- The less complex PCB design and manufacturing process.
- Most of the time visual inspection is good enough, using a good magnifier.
- Less expensive solder paste is required.
- Less stress on PCB while desoldering.
- Less stress on thermal cycling, that’s why the reliability of these leaded packages are much higher than their lead-less counterparts.
So, next time when you are planning to use electronic IC and are not sure about which one to use, leaded or lead-less package, consider the above mentioned points.
Happy learning to you!