Printed Circuit Boards (PCBs) form the foundation of modern automotive electronic circuit. They are inevitable for making reliable interconnections. They support the assembly of electronic ignition systems, transmission control units, electronic lamp driving, navigation systems, and many others in a vehicle.

When manufacturing and assembling PCBs for automotive electronics, there are several factors to be taken care of. They must be built to withstand high temperatures, pressure, harsh chemicals, oils, and other contaminants. To endure aforementioned factors and to offer reliable performance, automotive PCBs are coated with premium grade finishes. Let us understand the advantages and disadvantages of few of the commonly used surface finishes.

Surface Finishes for Automotive PCBs – Advantages and Disadvantages

PCBs meant for automotive applications are generally coated using any of the four finishes listed below. Each finish has its own advantages and disadvantages.

Hot Air Solder Level (HASL)

• • Advantages – Can be easily applied, good bond strength, long shelf life, can be easily reworked, allow easy visual inspection, and low cost.
  • Disadvantages – Contains lead, bridging problems on fine pitch assemblies, and uneven surfaces.

Immersion Silver

• • • • Advantages – 6 -12 months shelf life, excellent solderability, short and easy process cycle, inexpensive, and can be reapplied and reworked easily.
      • Disadvantages – Sensitive to electrical test and high friction coefficient.

Electroless Nickel/Immersion Gold (ENIG)

• • • • • • Advantages – Good for PTH (Plated Through Holes), consistent thickness, solders easily, good contact resistance, flat and planar surface.
          • Disadvantages – Difficult to rework on, and complicated to apply.

Organic Solderability Preservative – (OSP)

• • • • • • • • Advantages – Cost effective and simple process, well suited to tight-pitch pads, good solder mask integrity, doesn’t affect final hole size.
              • Disadvantages – Thickness cannot be measured precisely, not a good option for plated through hole, short shelf life, requires relatively aggressive flux at assembly, difficult to inspect, and sensitive to handling.

Now that you know the pros and cons of different types of surface finishes used for automotive PCB assembly. The next is taking a call on the right finish. Choosing the right finish largely contributes to the functionality and service life of the final assembly. Your selection must be depended on factors such as budget, application method, shelf life, testability, and compatibility with the overall assembly processes, among several others. If you like to know more information about printed circuit boards, please visit the website http://www.rigiflex.com or Call us at (714) 688-1500