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Solder Alloy Plating

Electroplating & electroless plating · Electrolytic bath

Solder plating deposits tin-lead or lead-free tin-alloy material on terminals, busbars, lids, and machined electronic parts to provide a controlled solderable surface.

CNC machiningSheet metalStandard cost $$Conductive
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Reference page — Solder plate is not in the instant-quote configurator. Upload the part, name the finish in the notes, and an engineer quotes it with the part.

Solder Alloy Plating on a machined part

What is Solder plate?

It is relevant where a drawing requires a solder alloy rather than pure tin.

How it works

The cleaned and activated part is cathodically plated from an electrolyte containing tin and the selected alloying metal. Tin-lead processes commonly target eutectic or near-eutectic composition; lead-free alternatives include tin-copper and tin-bismuth, selected for assembly temperature and reliability. A nickel underplate can limit copper diffusion. Reflow may homogenize composition and improve wetting, while electrolytic current distribution still creates edge-to-recess thickness variation.

Why specify it

  • Supplies a ready-solderable 5–25 µm surface
  • Alloy can match the assembly solder process
  • Reflow can verify wetting and homogenize deposit
  • Useful on busbars, terminals, lids, and electronic housings

Where it falls short

  • Tin-lead is restricted by RoHS except exemptions
  • Lead-free alloys need higher or different reflow profiles
  • Composition must be measured and controlled
  • Tin-rich deposits retain whisker concerns

Solder plate at a glance

Solder plate is a middle-of-the-range finish; its best score is corrosion protection (42 of 100), at a standard cost. It adds little surface hardness.

Corrosion protectionFair42 / 100
Surface hardnessMinimal9 / 100
Cosmetic qualityFair35 / 100
LubricityFair35 / 100
Relative costStandard30 / 100
CorrosionHardnessCosmeticLubricityEconomy

Each score is 0–100 against every finish in this catalog. Corrosion comes from salt-spray life (ASTM B117, log scale) and hardness from the finish layer's Vickers or pencil hardness; cosmetic, lubricity and cost are FabDigit's engineering assessment. Economy on the radar is the inverse of cost.

Solder plate key numbers

Typical values from the governing specifications and shop practice; bars are this finish against the highest value among electroplating & electroless plating finishes.

Thickness5–25 µm0.2–0.98 mil
Hardness10–30 HV
Thickness
5–15 µm for terminals and solderable hardware; 15–25 µm where reflow or heavier solder reserve is specified
Hardness
10–30 HV — Soft alloy deposit; composition and reflow condition control hardness.
Electrical
Conductive
Colours
  • silver gray
Appearance
Matte to bright silver-gray; reflow produces a smoother fused surface.

Where Solder plate sits among all finishes

Surface hardness (Vickers, log scale) against corrosion protection (salt-spray hours, log scale) for every coating FabDigit offers, one cloud per finish group. Solder plate is highlighted; hover a dot for its name or open the full map.

02550751000255075100Corrosion protection (0–100)Surface hardness (HV, log scale, 0–100)Plating — 19 finishesHard coatings — 17 finishesAnodize & conversion — 8 finishesPaint & powder — 7 finisheshard, low corrosion protectionhard and protectiveprotective, softsoft, little protectionType II anodize — corrosion 71, hardness 54BSA anodize — corrosion 71, hardness 52Type I anodize — corrosion 71, hardness 49Hard anodize — corrosion 71, hardness 61PTFE hard anodize — corrosion 71, hardness 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Cadmium plate — corrosion 70, hardness 26Copper plate — corrosion 32, hardness 39Decorative chrome — corrosion 64, hardness 71Electroless copper — corrosion 20, hardness 41Electroless nickel — corrosion 70, hardness 68Nickel plate — corrosion 51, hardness 55Gold plate — corrosion 68, hardness 39Hard chrome — corrosion 40, hardness 73Hot-dip zinc — corrosion 90, hardness 42Nickel-PTFE — corrosion 72, hardness 57Silver plate — corrosion 55, hardness 39Tin plate — corrosion 34, hardness 0Zinc plate — corrosion 60, hardness 30Zinc-nickel — corrosion 86, hardness 60Cerakote — corrosion 83, hardness 27E-coat — corrosion 83, hardness 15Epoxy coat — corrosion 83, hardness 15Powder coat — corrosion 83, hardness 14Wet paint — corrosion 59, hardness 10AlCrN PVD — corrosion 58, hardness 93AlTiN PVD — corrosion 52, hardness 94CrN PVD — corrosion 62, hardness 83DLC — corrosion 55, hardness 93MoS2 PVD — corrosion 20, hardness 26TiAlN PVD — corrosion 50, hardness 93TiCN PVD — corrosion 40, hardness 92TiB2 PVD — corrosion 40, hardness 94TiN PVD — corrosion 45, hardness 87WC/C PVD — corrosion 48, hardness 77ZrN PVD — corrosion 52, hardness 90CVD alumina — corrosion 70, hardness 85CVD TiCN — corrosion 38, hardness 92CVD TiN — corrosion 45, hardness 87Multilayer CVD — corrosion 62, hardness 88HVOF coating — corrosion 78, hardness 77Plasma spray — corrosion 60, hardness 68Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERTin plateSilver plateType II anodizePowder coatZinc plateZinc-nickelHard chromeDLCTiN PVDCadmium plateE-coatCerakoteWet paintHot-dip zincNitridingHVOF coatingSolder plate — corrosion 42, hardness 9Solder plate
02550751000255075100Corrosion protection (0–100)Surface hardness (HV, log scale, 0–100)Plating — 19 finishesHard coatings — 17 finishesAnodize & conversion — 8 finishesPaint & powder — 7 finishesType II anodize — corrosion 71, hardness 54BSA anodize — corrosion 71, hardness 52Type I anodize — corrosion 71, hardness 49Hard anodize — corrosion 71, hardness 61PTFE hard anodize — corrosion 71, hardness 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Cadmium plate — corrosion 70, hardness 26Copper plate — corrosion 32, hardness 39Decorative chrome — corrosion 64, hardness 71Electroless copper — corrosion 20, hardness 41Electroless nickel — corrosion 70, hardness 68Nickel plate — corrosion 51, hardness 55Gold plate — corrosion 68, hardness 39Hard chrome — corrosion 40, hardness 73Hot-dip zinc — corrosion 90, hardness 42Nickel-PTFE — corrosion 72, hardness 57Silver plate — corrosion 55, hardness 39Tin plate — corrosion 34, hardness 0Zinc plate — corrosion 60, hardness 30Zinc-nickel — corrosion 86, hardness 60Cerakote — corrosion 83, hardness 27E-coat — corrosion 83, hardness 15Epoxy coat — corrosion 83, hardness 15Powder coat — corrosion 83, hardness 14Wet paint — corrosion 59, hardness 10AlCrN PVD — corrosion 58, hardness 93AlTiN PVD — corrosion 52, hardness 94CrN PVD — corrosion 62, hardness 83DLC — corrosion 55, hardness 93MoS2 PVD — corrosion 20, hardness 26TiAlN PVD — corrosion 50, hardness 93TiCN PVD — corrosion 40, hardness 92TiB2 PVD — corrosion 40, hardness 94TiN PVD — corrosion 45, hardness 87WC/C PVD — corrosion 48, hardness 77ZrN PVD — corrosion 52, hardness 90CVD alumina — corrosion 70, hardness 85CVD TiCN — corrosion 38, hardness 92CVD TiN — corrosion 45, hardness 87Multilayer CVD — corrosion 62, hardness 88HVOF coating — corrosion 78, hardness 77Plasma spray — corrosion 60, hardness 68Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERTin plateSilver plateZinc plateSolder plate — corrosion 42, hardness 9Solder plate
Anodize & conversionPlatingPaint & powderHard coatings

Specifications for Solder plate

The documents a drawing cites to define this finish, with the Type / Class rows that apply. Each links to a page explaining the standard.

Drawing call-out

LEAD-FREE Sn-0.7Cu SOLDER PLATE, 10–15 µm, OVER 2.5 µm MIN NICKEL UNDERPLATE; REFLOW AND VERIFY SOLDERABILITY PER CUSTOMER SPECIFICATION; RoHS COMPLIANT

Which materials take Solder plate?

Verdict per material family, with the grades that behave differently. Each family links to its datasheets in the material library.

Material familyVerdictNotes
Brass
YesCommon solderable hardware substrate after cleaning; nickel underplate is often used.
Copper Alloy
YesPrimary terminal and busbar substrate, commonly with nickel barrier.
Steel
With careRequires underplate and corrosion protection at cut edges.
Aluminum
LimitedRequires specialized activation and multilayer underplating.
DMLS / SLM
LimitedOnly for metal AM electrical hardware after porosity review.
Stainless Steel
LimitedRequires aggressive activation; nickel underplate is usual if specified at all.
Zinc Alloy
LimitedPossible on some hardware after a strike.
FDM
NoFused-filament polymers are incompatible with this process.
Magnesium Alloy
NoIncompatible.
MJF
NoPolymer powder-bed prints are incompatible with this process.
Polymer
NoOrganic polymers cannot take this inorganic metal-finishing process.
SLA
NoPhotopolymer prints are incompatible with this process.
SLS
NoPolymer powder-bed prints are incompatible with this process.
Titanium
NoTitanium is not a solder-plate substrate.

How Solder plate is applied, and what it does to the part

  1. 1Clean
  2. 2Activate
  3. 3Nickel underplate if required
  4. 4Plate controlled solder alloy
  5. 5Rinse
  6. 6Optional reflow
  7. 7Composition and solderability test
DimensionsAllow 5–25 µm solder plus underplate; molten reflow can redistribute material at edges and holes.
Build-up per side5–25 µm — Electrolytic deposit plus any nickel underplate; edges build faster than recesses.
MaskingUsually needed. Mask weld zones, contact surfaces requiring another finish, threads, and hermetic-seal lands as applicable.
ElectricalConductive
AppearanceMatte to bright silver-gray; reflow produces a smoother fused surface.
Added lead time4–8 working days on top of the bare part

Design rules for Solder plate

What to decide on the drawing before the part goes to the finisher.

  1. Name alloy composition and tolerance.Tin-lead, tin-copper, and tin-bismuth reflow differently.
  2. Specify lead-free status explicitly.Tin-lead is restricted unless a documented exemption applies.
  3. Define underplate.Nickel controls copper diffusion and intermetallic growth.
  4. Qualify the assembly thermal profile.Lead-free alloy liquidus and wetting differ from Sn-Pb.

Solder plate versus the alternatives

Finishes engineers weigh against Solder plate, and when each wins.

FinishCorrosionHardnessCosmeticCostThicknessChoose it when
Solder plate
this page
42935$$5–25 µm—
Tin Plating
Solder plate vs Tin Plating →
34045$$3–15 µmwhen pure matte tin satisfies solderability and whisker controls
Silver Plating
Solder plate vs Silver Plating →
553972$$$$5–20 µmwhen high-current conductivity and solderability are both required
CorrosionHardnessCosmeticLubricityEconomy
Solder plateTin Plating

The radar overlays Solder plate with Tin Plating, its most common alternative — chosen when pure matte tin satisfies solderability and whisker controls. Scores in the table are 0–100 across every finish in the catalog.

Cost, lead time and compliance

Relative cost

Solder Alloy Plating is a standard-cost finish ($$): cheaper than about 67 % of the finishes FabDigit quotes.

Finishing is priced per part with a lot minimum, from FabDigit's own China-side rates. The exact figure appears on the instant quote once the part is uploaded.

Lead time and compliance

Added lead time4–8 working days
RoHSRestricted
NotesTin-lead is restricted except applicable exemptions; lead-free alloy must be explicitly named and supplier-certified.

What Solder plate is used for

  • Solderable terminals
  • Busbars
  • Electronic package lids
  • Grounding lugs
  • Machined connector parts

Solder plate — frequently asked

tin plating vs solder plating

Tin plating is nominally pure tin, commonly 3–15 µm. Solder plating intentionally includes another metal such as lead, copper, or bismuth and is commonly 5–25 µm to match an assembly process.

is tin lead plating RoHS compliant

Generally no, because lead exceeds the RoHS homogeneous-material limit unless a specific exemption applies. Use a named lead-free alloy or document the product exemption.

what lead free solder can be plated

Tin-copper and tin-bismuth are among practical plated lead-free systems, while pure matte tin is also common. The assembly temperature, whisker plan, ductility, and supplier capability determine the correct alloy.

how thick is solder plating

Solderable hardware commonly uses 5–15 µm, while 15–25 µm can provide a larger solder reserve or support reflow. Include any nickel underplate separately.

does solder plating need reflow

Not always, but reflow can homogenize alloy, reduce porosity, and demonstrate wetting. It can also redistribute a 5–25 µm deposit and expose heat-sensitive substrate issues.