Surface Finish
Printed circuit board surface finish application is one of the final steps in the manufacturing process and is designed to prevent oxidation of the remaining exposed copper. Selecting the appropriate surface finish is a critical material decision due to importance it plays in electronic assembly. The surface finish will influence the cost, manufacturability, quality, and reliability of the final product.
The chart below lists many of the surface finish options offered by Sunking Circuits and provides some information regarding the characteristics and applications for each. If you’re unsure which surface finish is best for your project, contact us and we’ll be happy to assist you.
Characteristics | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| HASL | HASL (LF) | ENIG | ENEPIG | HARD GOLD | SOFT GOLD | SILVER | OSP | WHITE TIN | |
| Deposit | Dipped | Dipped | Immersion | Immersion | Electrolytic | Electrolytic | Immersion | Dipped | Immersion |
| Process Control | Poor | Poor | Fair | Fair | Fair | Fair | Fair | Poor/Fair | Fair |
| Process Cost | Low | Low | Medium | High | High | High | Medium | Low | Medium |
| SMT | Dome | Dome | Flat | Flat | Flat | Flat | Flat | Flat | Flat |
| Thin Board Finish | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Thermal Cycle (times) | >2 | >3 | >2 | >2 | >2 | >2 | >2 | ~2 | >2 |
| Shelf Life | Long (1+ Yrs) | Long (1+ Yrs) | Long (1+ Yrs) | Long (1+ Yrs) | Long (1+ Yrs) | Long (1+ Yrs) | Medium (9-12 Mos)* | Medium (9-12 Mos)* | Medium (9-12 Mos)* |
| Handling | Normal | Normal | Normal | Normal | Normal | Normal | Critical | Critical | Critical |
| Exposed Copper | No | No | No | No | Yes | No | No | Yes | No |
| Contact Applications | No | No | Yes | Yes | Yes | Yes | No | No | No |
| Thickness | 25 – 2000μin | 25 – 2000 μin | 3 – 10 μin of Gold over 150 – 200 μin of Nickel | 1 – 2 μin of Gold over 4 – 8 μin or 8 – 15 μin Palladium over 100 -150 μin Nickel | 98% Pure, 23 Karat 30 – 50 μin over 100 – 150 μin of Nickel | 99.99% Pure, 24 Karat 30 – 50 μin over 100 – 200 μin of Nickel | 6 – 18μin | 8 – 24μin | 25 – 60μin |
Application | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| HASL | HASL (LF) | ENIG | ENEPIG | HARD GOLD | SOFT GOLD | SILVER | OSP | WHITE TIN | |
| RoHS Compliant | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Fine Pitch SMT | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| BGA & μBGA | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Flip Chip | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Wire Bonding | No | No | Yes (Al) | Yes | No | Yes (Au) | No | No | No |
| Contact / Connector | No | No | Yes | Yes | Yes | No | No | No | No |
| High Reliability | High | Low/Medium | High | High | Medium/High | High | Medium/High | Medium/High | High |
| Solder Joint Integrity | Excellent | Good | Good | Good | Poor | Poor | Excellent | Good | Good |
* Requires Unique Storage Techniquesμin = Microinches
