Immersion Silver
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- Immersion Silver
0.12–0.40µm
Standard silver thickness (IPC-4552)
6+
Months typical storage shelf life
0
Lead — fully RoHS / WEEE compliant
20yrs
PCB manufacturing experience
What is immersion silver?
Immersion silver (ImAg) is an electroless finish applied over bare copper. Silver deposits out of a chemical bath onto the copper surface, forming a thin, flat, fully lead-free layer that protects the copper and stays solderable through assembly.
How it works
solution. Through an immersion (displacement) reaction, a uniform layer of high-purity silver is deposited — no electric current is used.
Why it matters
At a glance
- Lead-free, RoHS & WEEE compliant
- Flat and coplanar — ideal for fine pitch
- Good solderability and wire bonding surface
- Cost-effective alternative to ENIG
How we plate immersion silver
Six controlled stages on an inline or batch line. Each step is monitored and logged so thickness stays inside the IPC-4552 window and the surface stays clean and active for soldering.
Cleaning & micro-etch
The copper surface is cleaned of residues and micro-etched to remove the oxide layer, exposing a fresh, uniformly active copper surface. This step directly controls final silver adhesion and uniformity.
Pre-dip / conditioning
A pre-dip conditions the etched surface and prevents drag-in of etchant into the silver bath, keeping the immersion chemistry stable and preventing rough or patchy deposits.
Immersion silver deposition
In the silver bath, a displacement reaction deposits a uniform, dense silver layer directly onto the copper. No electric current is applied — the reaction is self-limiting, giving a flat, conformal finish.
Post-dip rinse
Multiple counter-current rinses remove residual chemistry. Clean rinsing prevents ionic contamination that could later cause tarnishing or reduce solderability.
Anti-tarnish treatment
A final anti-tarnish / stabilizer step protects the silver from sulfidation and tarnishing during storage and transport, extending usable shelf life without affecting solderability.
Inspection & thickness verification
Each lot is checked for silver thickness (X-ray fluorescence), surface appearance and solderability. Results are recorded and traceable to your order.
Key performance properties
Immersion silver balances flatness, solderability and cost. Here is what the finish delivers across the properties that matter in assembly.
Flatness & coplanarity
Thin, conformal deposit keeps pads flat and coplanar — essential for fine-pitch components and BGAs where uneven solder can cause open joints.
Solderability
Silver is highly solderable with tin-lead and lead-free solders, giving strong wetting and reliable joints across repeated reflow.
Electrical performance
Excellent contact resistance and high-frequency behavior, suitable for RF and microwave boards where signal integrity matters.
Lead-free
Fully RoHS and WEEE compliant with no lead in the finish, ready for export to EU and other restricted-markets.
Where immersion silver shines
Choose immersion silver when flatness, solderability and lead-free compliance matter more than the lowest possible material cost.
High-density interconnect (HDI)
Fine lines, microvias and dense pad layouts benefit from a flat finish that keeps fine-pitch joints reliable.
RF & microwave boards
Consistent surface and low insertion loss make immersion silver well-suited to high-frequency signal paths.
LED & lighting
Good solderability and a bright, uniform surface suit LED modules and lighting driver boards.
Automotive electronics
Reliable joints and lead-free compliance fit the durability demands of automotive control and driver boards.
Consumer & IoT
Cost-effective lead-free finish for wearables, smart-home and consumer electronics PCBs.
Backplanes & servers
Flat, durable pads for dense connectors and repeated assembly in server and networking equipment.
Shelf life & tarnishing — what to know
Immersion silver is a silver finish, so it can tarnish if exposed to sulfides and humidity. Here is how we protect it and how you can maximize its shelf life.
Typical storage shelf life
6 – 12 months under recommended storage conditions
Best within 6 months for consistent solderability
Store in sealed, moisture-barrier packaging with desiccan
Keep at low humidity; avoid sulfur-containing environments
How we reduce tarnishing
Anti-tarnish post-treatment on every board
Clean, controlled rinse to avoid ionic residue
Moisture-barrier vacuum packaging for shipment
Clear storage & handling guidance with every order
Frequently asked questions
Straight answers to the questions engineers and buyers ask most about immersion silver.
What is the difference between immersion silver and ENIG?
ENIG uses an electroless nickel layer under an immersion gold layer (nickel-gold). Immersion silver is a single silver layer directly on copper. ENIG is more corrosion-resistant but costs more and adds nickel layers. Immersion silver is flatter, cheaper and lead-free, with excellent solderability — the trade-off is a shorter shelf life and some tarnishing risk if mishandled.
How long does immersion silver last?
Under proper sealed, low-humidity storage, immersion silver typically lasts 6 to 12 months while keeping good solderability. We recommend soldering within 6 months for best results and verify solderability before assembly for older stock.
Is immersion silver good for fine-pitch / HDI boards?
Yes. The flat, uniform deposit avoids the uneven thickness that causes solder bridging or opens on fine-pitch pads and BGAs. That flatness is one of the main reasons immersion silver is chosen for HDI and high-density designs.
Does immersion silver tarnish? How do you prevent it?
Silver can tarnish when exposed to sulfides and humidity. We prevent it with an anti-tarnish post-treatment, clean rinsing and moisture-barrier packaging. Storing boards sealed and away from sulfur sources keeps them clean until soldering.
What is the typical immersion silver thickness?
Typical deposited thickness is 0.12 to 0.40 µm, with a common target of 0.15–0.30 µm. We verify thickness with X-ray fluorescence and report it per IPC-4552 so you know exactly what you are getting.
Is immersion silver RoHS compliant?
Yes. Immersion silver is fully lead-free and complies with RoHS, WEEE and REACH, making it suitable for export to restricted-market regions including the EU.
How much does immersion silver cost?
Immersion silver is generally more affordable than ENIG (no nickel-gold layers) while costing slightly more than HASL or OSP. Final cost depends on board area, layer count, quantity and finish coverage. Send us your Gerber files for an exact quote.
Can immersion silver boards be reflowed multiple times?
Immersion silver is designed to withstand multiple reflow cycles typical of double-sided and mixed SMT assembly, keeping good wetting across passes. Verify solderability for boards stored near the end of their shelf life before extended reflow.
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