Surface Finish Is the Connection between Copper PAD and SMT Solder
Similar to solder mask, however, surface finish does not protect copper trace but the exposed copper PAD after solder mask process. As the connection between copper PAD and SMT solder, a few common options and comparison are as below.
OSP (Organic Solder-ability Preservative)
Advantage: low cost / good flatness / good solder-ability
Disadvantage: short storage time / not good for second time reflow
Lead Free HASL (Hot Air Solder Level)
Advantage: better cost / good solder-ability / better storage time
Disadvantage: bad flatness / not good for small component
ENIG (Electro-less Nickel Immersion Gold)
Advantage: long storage time / good flatness / good for second time reflow
Disadvantage: high cost / less welding strength
OSP (Organic Solder-ability Preservative)
Advantage: low cost / good flatness / good solder-ability
Disadvantage: short storage time / not good for second time reflow
Lead Free HASL (Hot Air Solder Level)
Advantage: better cost / good solder-ability / better storage time
Disadvantage: bad flatness / not good for small component
ENIG (Electro-less Nickel Immersion Gold)
Advantage: long storage time / good flatness / good for second time reflow
Disadvantage: high cost / less welding strength
Maybe you would like to read more:
- Working panel vs. shipping panel, the different size during PCB production.
- One of the surface finish of PCB, Carbon
- The differences and application of hard gold plating and soft gold plating.
- How is the Number of PCB Layers Counted? What is the Difference between Double Sided PCB and Multi-layer PCB?