Solving the Surface Finish Selection Paradox for Next Generation PCB Technologies
Key Summary
• Surface finish selection is critical for performance and reliability in next generation PCBs
• Key criteria include insertion loss, solder joint reliability, shelf life, reflow durability, and cost
• Different finishes affect solder joint strength and intermetallic formation
• Supply chain disruptions highlight the importance of finishes with longer shelf life
• The PD course covers roles, criteria, and pros and cons of available surface finishes
Surface finish is applied on to copper (Cu) integration scheme on printed circuit boards (PCBs). Choice of surface finish is critical especially for next generation HDI, high frequency PCBs because the performance and reliability of the electronic assemblies depends on the right selection. I hope you will join me for my professional development course, PD05: Role and Selection Criteria of Surface Finish for Next Generation PCB Technologies - 5G, HDI, RF-Microwave, High Frequencies, March 11, at IPC APEX EXPO 2021, where I will discuss this in detail.
There are several surface finish options available on the market and one (OEM, PCB manufacturers, PCB designers, EMS) needs to consider the following critical selection criteria,
- Insertion loss: Next generation electronic assemblies require HDI, high frequency PCBs. Right choice of surface finish is critical to attain optimum signal integrity with minimal insertion loss.
- Solder joint reliability: Few surface finishes options (i.e., ENIG, etc.) tend to form brittle solder joints with lead-free solder. Also, Ni based surface finishes form Sn-Ni intermetallics/solder joints which are less strong to Sn-Cu intermetallics. Can the surface finish participate in ensuring smaller intermetallics and robust solder joints? The choice of the surface finish is critical in ensuring robust solder joints in your final assembly.
- Shelf life: Looking at the current pandemic situation going on around the world, longer shelf life is critical due to supply chain disruptions across the world.
- Reflow cycles during assembly: With ever-increasing complexity of the electronic assemblies, it is paramount to have the surface finish that can withstand multiple reflow cycles (3+).
- Cost-effective: It is also critical to review cost during the selection of the surface finish. There are few options that involve use of precious metals, i.e., Ag, Au, Palladium (Pd). Thickness of these precious metals-based surface finishes are critical to ensure cost-effectiveness.
Overall performance and reliability of electronic assemblies depends on the right material selection of every component involved. The surface finishes on the PCBs are critical piece to ensure the optimum performance and reliability of the electronic assemblies. Pay attention while selecting surface finishes for next generation PCB technologies.
What you will learn from my PD course:
- Role of surface finish for next generation PCB technologies
- 5G, HDI, RF-Microwave, High Frequencies
- Selection criteria of surface finish for next generation PCB technologies
- 5G, HDI, RF-Microwave, High Frequencies
- Currently available surface finish options in the market and their pros and cons
Surface finishes influence signal integrity, solder joint strength, reliability, and overall assembly performance. As HDI and high frequency designs advance, choosing the correct finish becomes essential for achieving stable, high-performing electronic assemblies.
High frequency and HDI assemblies depend on low insertion loss to maintain signal integrity. Selecting a finish that supports minimal loss helps ensure reliable performance in demanding applications like 5G and RF technologies.
Some finishes, such as ENIG or nickel-based coatings, can form brittle or weaker intermetallics under lead-free solder. Choosing a finish that supports stronger solder joints helps improve long-term durability in complex assemblies.
Global supply chain disruptions make long component life critical. A finish with better shelf stability allows manufacturers to store materials longer without risking oxidation or performance issues during assembly.
The course reviews the role of surface finishes in next generation PCB technologies, key selection criteria, and available finish options. It also explains performance considerations for 5G, HDI, RF, microwave, and high frequency applications.