TABLE OF CONTENTS Table 14.1 lists the options of lead-free surface finishes for PCBs. The system is categorized by the key element used. Each category is further classified by the type of process and chemistry. Examples are given for certain groups.
| Surface finish system | Finish process and chemistry | Example |
|---|---|---|
| OSP | Benzotriazole | COBRATEC, ENTEK CU-56 |
| Imidazole | AT&T, Protecto 5630 (Kester) | |
| Benzimidazole (substituted) | ENTEK PLUS CU-106A (Enthone-OMI), Glicoat (Shikoku) | |
| Preflux (rosin/resin) | Sealbrite, Solderite RT-05R | |
| Ni-Au | Electrolytic Ni-Au, or EG | |
| Electroless Ni/electroless (immersion) Au, or ENIG | ||
| Electroless Ni/electroless (autocatalytic) Au | ||
| Electroless Ni/electroless (substrate-catalyzed) Au | ||
| Ag | Electroless (immersion, or galvanic) Ag | Alpha Level (Alpha Metals); Sterling Silver (MacDermid) |
| Bi | Electroless (immersion) Bi | |
| Electrolytic Pd or Pd alloys | ||
| Pd | Electroless (autocatalytic) Pd | |
| Electroless (autocatalytic) Pd/electroless (immersion) Au | ||
| Ni-Pd | Electroless Ni/electroless (immersion) Pd | |
| Electroless Ni/electroless (autocatalytic) Pd | ||
| Electroless Ni/electroless (autocatalytic) Pd/electroless (immersion) Au | ||
| Ni-Pd ( X) | Electrolytic Ni/PdCo/Au flash | |
| (Electroless) Ni/(electroless) Pd-Ni/electroless (immersion) Au | ||
| Sn | Electrolytic Sn | Matte Lucent (large, polygonized) |
| Electrolytic Sn | Florida CirTech | |
| Electrolytic Sn | ||
| Electroless (immersion) Sn | White (new) | |
| Electroless (immersion) Sn | Gray (old) | |
| Electroless (modified immersion + autocatalytic) Sn | Flat Solderable Tin (FST) Dexter | |
| Ni-Sn | Electrolytic Ni/electrolytic Sn | Satin bright Sn Lucent ECS |
| Sn-Ag | Electrolytic Sn-Ag | 96.5Sn-3.5Ag |
| Electrolytic Sn-Bi | 90Sn-10Bi | |
| Sn-Bi | Electroless (immersion) Sn-Bi | Motorola |
| Sn-Cu | Electrolytic Sn-Cu | 99Sn-1Cu |
| Sn-Ni | Electrolytic Sn-Ni | |
| * For multilayer designs, the sequence of materials starts from the bottom layer. |
