# PCB Surface Finish Comparison: HASL vs ENIG vs OSP and More > Source: https://netray.co/tools/pcb-surface-finish-comparison-hasl-enig-osp-reference > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: Free Tools ## Short answer Side by side comparison of common PCB surface finishes with flatness, shelf life, wire bond and typical use. ## Category electronics ## Industry Electronics Manufacturing ## Audience - PCB designer - Buyer - PCBA process engineer ## Tool **Kind:** worksheet **Mode:** reference **Columns:** #### Finish **Key:** finish **Type:** text #### Full name **Key:** full_name **Type:** text #### Pad flatness **Key:** flatness **Type:** text #### Typical shelf life **Key:** shelf **Type:** text #### Fine pitch suitability **Key:** fine_pitch **Type:** text #### Wire bonding **Key:** wire_bond **Type:** text #### Watch for **Key:** watch **Type:** text **Rows:** **Finish:** HASL **Full name:** Hot air solder leveling, tin lead **Flatness:** Uneven, domed pads **Shelf:** About 12 months **Fine pitch:** Poor **Wire bond:** No **Watch:** Thickness variation, thermal shock to the board, restricted for many RoHS products **Finish:** LF HASL **Full name:** Lead free hot air solder leveling **Flatness:** Uneven, domed pads **Shelf:** About 12 months **Fine pitch:** Poor **Wire bond:** No **Watch:** Higher process temperature stresses the laminate **Finish:** ENIG **Full name:** Electroless nickel immersion gold **Flatness:** Very flat **Shelf:** About 12 months **Fine pitch:** Good **Wire bond:** Limited **Watch:** Black pad defect, gold embrittlement risk with thick gold, cost **Finish:** ENEPIG **Full name:** Electroless nickel electroless palladium immersion gold **Flatness:** Very flat **Shelf:** About 12 months **Fine pitch:** Good **Wire bond:** Yes **Watch:** Higher cost, fewer suppliers **Finish:** ImAg **Full name:** Immersion silver **Flatness:** Flat **Shelf:** About 6 to 12 months **Fine pitch:** Good **Wire bond:** Limited **Watch:** Tarnish in sulfur rich air, handle with gloves, microvoids **Finish:** ImSn **Full name:** Immersion tin **Flatness:** Flat **Shelf:** About 6 months **Fine pitch:** Good **Wire bond:** No **Watch:** Tin whiskers, limited reflow cycles, press fit compatibility **Finish:** OSP **Full name:** Organic solderability preservative **Flatness:** Flat **Shelf:** About 3 to 6 months **Fine pitch:** Good **Wire bond:** No **Watch:** Handling damage, limited reflow passes, hard to inspect, low cost **Finish:** Hard gold **Full name:** Electrolytic nickel and hard gold **Flatness:** Flat **Shelf:** Long **Fine pitch:** Not for general soldering pads **Wire bond:** Yes, with suitable gold **Watch:** Used for edge connectors and contacts, costly, needs plating bars **Finish:** Soft gold **Full name:** Electrolytic nickel and soft gold **Flatness:** Flat **Shelf:** Long **Fine pitch:** Specialist use **Wire bond:** Yes **Watch:** Used for wire bonding, high cost **Finish:** ENIG plus OSP **Full name:** Selective combination finish **Flatness:** Flat **Shelf:** Varies by area **Fine pitch:** Good **Wire bond:** Per area **Watch:** Extra process steps, confirm with the fabricator **Notes:** Shelf life values are typical industry ranges for properly packed boards and vary by fabricator and storage conditions. Confirm with your PCB supplier and the IPC specifications for each finish before specifying. ## Content **Intro:** Choosing a surface finish is a trade-off between flatness, cost, shelf life, assembly process and reliability. This comparison table puts the common finishes side by side so designers and buyers can narrow the choice before talking to the fabricator. **Sections:** #### How to use the comparison **Body:** Start with the hardest requirement: fine pitch BGAs need flat pads, wire bonding limits the choice to a few finishes, and edge connectors need hard gold. Then look at shelf life against your inventory turns and how many reflow passes the board sees. Finally compare cost. Export the table and add your own columns for supplier lead time and price. #### Standards and specifications **Body:** IPC-4552 covers ENIG, IPC-4553 immersion silver, IPC-4554 immersion tin, IPC-4556 ENEPIG and IPC-6012 the qualification for rigid boards. J-STD-003 covers solderability testing of printed boards. Reference these in the fabrication notes so the fabricator and your incoming inspection work from the same criteria. **Bullets:** - State the finish, thickness range and standard in the fab drawing - Specify solderability testing if boards are stored for long periods - Ask for the packing method, vacuum bags protect OSP and ImAg #### Worked example **Body:** A board with 0.4 mm pitch BGAs and a long storage time between builds needs flat pads and a reasonable shelf life. HASL is ruled out by flatness, OSP by shelf life, which leaves ENIG or ENEPIG. If no wire bonding is needed, ENIG with a controlled process is the usual choice, and the team adds a black pad check to incoming inspection. #### Common mistakes **Body:** Specifying a finish only by name leaves thickness and quality open. Another mistake is storing OSP boards for months and then complaining about wetting. Mixing finishes inside one lot because of supplier changes can also change your process window, so record the finish on the receiving inspection. **Cta:** If your ERP tracks PCB lots, Netray can help flag boards approaching shelf life limits before they reach the line. **Faq:** #### Which is better, HASL or ENIG? **Answer:** ENIG gives flatter pads and suits fine pitch parts. HASL is cheaper and robust for through hole boards but pads are uneven. The right choice depends on package pitch, cost targets and any compliance needs. #### What is black pad? **Answer:** Black pad is a failure mode in ENIG where the nickel layer is corroded during gold plating, causing weak solder joints. Good fabricator process control and incoming inspection reduce the risk. #### How long can OSP boards be stored? **Answer:** Typically around three to six months in sealed packaging, but it varies by supplier. Open bags and long delays before the second reflow cause wetting problems, so follow the fabricator's guidance. #### Can I use ENIG for wire bonding? **Answer:** Standard ENIG is limited for wire bonding. ENEPIG or specific gold finishes are normally specified for that purpose. Confirm with your bonding process owner. ## Search terms pcb surface finish comparison, hasl vs enig, enig vs osp, immersion silver vs immersion tin, enepig surface finish, pcb finish shelf life, which pcb surface finish to choose, lead free hasl --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json