PCB surface finishes, also known as PCB surface treatments, involve applying a layer of metal or compound on the copper pads of printed circuit boards (PCBs) using chemical or physical methods. These finishes serve two key purposes: first, to prevent copper pads from oxidizing, and second, to ensure the PCBs are easy to solder during assembly.
At ESPCBA, we provide a wide range of PCB surface finishes to meet various application needs:
ENIG (Electroless Nickel Immersion Gold) involves covering the copper surface with a layer of nickel and gold. This finish offers excellent oxidation resistance and has a long shelf life (up to 12 months). Its superior electrical performance makes it ideal for high-density PCBs, thanks to gold’s excellent conductivity.
Immersion Silver coats the copper pads with silver through a chemical displacement reaction. This finish provides excellent conductivity and solderability at a lower cost than gold. However, immersion silver can discolor in normal environments.
Immersion Tin applies a tin layer to the copper pads, providing effective protection from oxidation and excellent solderability. Its smooth surface makes it a better choice than HAL, though it comes with a higher cost.
ENEPIG adds a layer of palladium between nickel and gold, improving the finish’s durability and preventing defects caused by nickel migration. This treatment reduces the risk of black pad issues and enhances wiring and aging resistance.
HAL coats the copper pads with a layer of molten tin, which is leveled using hot air. HAL is a popular surface finish due to its cost-effectiveness and ease of production, though it is unsuitable for fine-pitch components and BGA due to its uneven surface.
OSP applies a thin organic layer to copper pads to prevent oxidation. It is a cost-effective finish that offers good solderability, though it is less thermally stable and has a shorter shelf life compared to other finishes.
Hard gold plating involves a nickel barrier layer followed by a gold layer, providing excellent oxidation resistance and solderability. Its durable, bright finish is commonly used on edge connectors that undergo frequent plugging.
oxidation resistance. Unlike hard gold, it is primarily used for soldering components onto PCB pads.
Some PCBs may use multiple surface finishes to leverage the advantages of different treatments. Common combinations include ENIG + OSP, ENIG + hard gold on edge connectors, and HAL + hard gold.
| Surface Finish | Cost | Shelf Life | Solderability | Advantages and Disadvantages |
|---|---|---|---|---|
|
HAL with Lead |
Normal |
12 months |
High |
Cost-effective and highly efficient. Excellent solderability, but not RoHS/Reach compliant. Not suitable for BGA or fine-pitch applications. |
|
Pb-Free HAL |
Normal |
12 months |
High |
RoHS compliant and cost-effective. Suitable for most applications, but not ideal for BGA and fine-pitch components. |
|
OSP |
Low |
3 months |
Normal |
Economical, but has limited thermal stability and is unsuitable for PTH & SMT mixed assembly or EMI areas. |
|
Plating Gold |
High |
12 months |
High |
Excellent solderability, conductivity, and long shelf life. High cost and risk of embrittlement in solder joints. |
|
Immersion Gold |
High |
12 months |
High |
Smooth surface with excellent electrical performance. Long-lasting, but may experience black pad defects. |
|
Immersion Silver |
Normal |
12 months |
High |
Cost-effective with good conductivity, but sensitive to sulfur and prone to discoloration. |
|
Immersion Tin |
Normal |
12 months |
High |
Smooth surface and excellent solderability. However, it requires careful chemical handling. |
|
ENEPIG |
High |
12 months |
High |
No risk of black pad defects, durable, and reliable. Ideal for high-performance PCBs but costly. |
| Surface Finish | Storage Condition & Shelf Life | Workshop Life After Unpacking |
|---|---|---|
|
Immersion Silver |
≤27°C, ≤60% humidity, no acids or alkalis |
≤48 hours |
|
OSP |
≤27°C, ≤60% humidity, no acids or alkalis |
≤24 hours |
|
ENIG, ENEPIG, Gold |
≤27°C, ≤60% humidity, no acids or alkalis |
≤24 hours |
|
Immersion Tin |
≤27°C, ≤60% humidity, no acids or alkalis |
≤24 hours |
|
HAL |
≤27°C, ≤60% humidity, no acids or alkalis |
≤24 hours |
Looking for reliable SMD assembly services? At ESPCBA, we’re your trusted partner for PCB fabrication, component sourcing, and electronic manufacturing. With over 16 years of experience, we’ve provided high-quality PCBs at competitive prices to over 1,000 customers worldwide. Our company is ISO9001:2015 certified and UL listed, and every product we deliver is 100% E-tested and inspected using AOI and X-ray to meet the highest standards. Get an instant quote from our sales team today, and let us handle the rest for you.
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inquiry@espcba.com