Kovar Surface Finishing

Why Kovar Surface Finishing Matters

Finishing Kovar is not “one process fits all.” Geometry, sealing method, and downstream assembly drive how surfaces should be prepared. Done right, it improves seal performance, ensures plating adhesion, removes micro-burrs, and preserves thin walls without distortion.

✓ Hermetic seal performance (glass-to-metal & ceramic-to-metal)

✓ Plating adhesion and uniform thickness

✓ Burr-free edges for sealing and assembly

✓ Controlled Ra for solderability, wire bonding, or sealing

✓ Thin-wall and small-feature preservation

✓ Consistent cosmetics for visible surfaces

Surface Finishing Capabilities for Kovar

Precision Deburring & Edge Conditioning

• Manual and mechanical micro-deburring
• Abrasive brush and media techniques tuned for Kovar
• Target edge break: 0.02–0.10 mm (0.001–0.004 in)

Surface Roughness (Ra) Control

• As-machined Ra: 0.8–3.2 µm (32–125 µin)
• Lapped/polished sealing lands: ~0.1–0.4 µm (4–16 µin)
• Uniform matte finishes via micro-blast

Sealing-Surface Preparation

• Localized lapping/polishing on gasket or glass-seal lands
• Controlled edge radii at seal interfaces per spec

Cleaning & Activation

• Precision degrease and alkaline clean
• Oxide removal and acid activation/pickling
• Optional vacuum/hydrogen bake-out

Plating Preparation & Coordination

• Nickel underplate (diffusion barrier)
• Gold for wire bonding and corrosion resistance
• Silver/tin for soldering or RF needs
• Selective/masked plating per drawing

Inspection & Documentation

• Profilometer Ra measurement, microscopy for burr control
• XRF plating thickness verification
• Dimensional, visual, cleanliness checks
• Full lot traceability

Plating may be performed by vetted finishing partners under KELTRYN control with full lot traceability and certification.

What We Finish

★ Housings and enclosures
★ Lids and caps
★ Sealing rings and flanges
★ Frames, carriers, and submounts
★ Thin-wall and small-feature components
★ Custom features for G-T-M and C-T-M sealing

All components machined from Kovar / ASTM F15 with full material traceability.

Typical Ra Targets by Function

Hermetic G-T-M / C-T-M sealing lands: 0.4–0.8 µm (16–32 µin)
Wire-bondable surfaces (after Ni/Au): per process spec; base metal prep supports adhesion
Solderable features: uniform matte clean surface; Ra 0.8–1.6 µm (32–63 µin) before plating

We collaborate with your engineering team to align Ra with sealing, bonding, or soldering requirements.

Common Kovar Plating Stacks We Support

Plating Stack	Typical Thickness	Application
Nickel underplate (electrolytic or electroless)	~5–12 µm (0.0002–0.0005 in)	Diffusion barrier, adhesion
Gold over nickel (thin)	0.5–1.0 µm (20–40 µin)	Corrosion protection, solderability
Gold over nickel (heavy)	1.0–2.5 µm (40–100 µin)	Robust wire bonding, extended storage
Silver over nickel	5–25 µm (0.0002–0.0010 in)	Application-driven (e.g., RF)
Tin over nickel	2.5–12 µm (100–500 µin)	Whisker-mitigation practices per spec

Standards commonly referenced: ASTM F15, ASTM B488, MIL-DTL-45204, ASTM B689, ASTM B733.

Design-for-Finishing Guidance

• Call out Ra only where functionally required; identify sealing lands explicitly
• Specify edge breaks or radii on sealing and assembly edges (typ. 0.02–0.10 mm)
• Define plating thickness and coverage (all surfaces vs. selective) and masking zones
• Account for plating buildup in tolerances: diameters change by ~2× plating thickness
• Threads: specify class/allowance or masking
• Avoid burr traps and inaccessible grooves; add reliefs/lead-ins
• Include datum strategies that survive finishing and plating
• For thin-walls: maintain minimum wall thickness and support features
• Provide cleaning/handling sensitivity notes (no touch on sealing faces; lint-free handling)

We review drawings and provide practical manufacturability feedback before release.

Tolerancing & Plating Allowance Tips

• For tight bores/pins, specify limits either pre-plate or post-plate — avoid ambiguity
• Critical sealing diameters often controlled pre-plate with masked coverage; if post-plate control required, allocate tolerance for buildup
• Threads: mask where functionally required, or define final class/fit with plating compensation

Example Process Flow

Material receipt and verification (ASTM F15, lot traceability)
CNC turning/milling and multi-axis machining with heat/work-hardening control
In-process deburring and protective fixturing for thin-walls
Localized finishing of sealing lands (lapping/polishing) to target Ra
Precision cleaning and activation for plating or sealing
Plating coordination (Ni/Au, Ag, Sn systems as specified), masking as required
Final deburr/clean, inspection (Ra, thickness, dimensions), and documentation
Protective packaging and reliable delivery

Quality, Traceability, and Documentation

📋

Material certificates and lot traceability end-to-end

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Surface finish data and visual inspection records

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Plating certifications and XRF thickness reports

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Dimensional inspection reports upon request

Industries and Applications

Hermetic electronic packaging Laser & photonics modules Semiconductor equipment Aerospace & defense electronics Medical & diagnostic instruments Vacuum & scientific instruments Sensor, RF, microwave, power electronics Glass-to-metal & ceramic-to-metal sealing

Frequently Asked Questions

What surface finish is best for glass-to-metal sealing?

Many seals target 0.4–0.8 µm Ra (16–32 µin) and a clean, defect‑free land. Your sealing process may dictate tighter or looser values—share your spec and we will align our finishing.

Do you provide gold over nickel plating on Kovar?

Yes, through vetted finishing partners with certification and XRF thickness verification. We also support selective/masked plating per drawing.

Can you control micro‑burrs on thin‑wall Kovar parts?

Yes. We use controlled feeds, sharp tooling, and purpose‑built micro‑deburring methods to remove burrs while protecting thin features and sealing faces.

How should I specify plating on threads and bores?

Indicate masking requirements or specify final dimensions/fit post‑plate with the target thickness. We can recommend allowances based on the selected stack.

What lead times do you support?

Prototype/low‑volume work typically begins shipping in 2–6 weeks depending on complexity, finishing, and plating load. Share your schedule and we’ll propose a realistic plan.

Request a Quote

Send your 2D drawing, 3D model, and any finishing/plating specifications:

• Material: Kovar / ASTM F15 / Fe‑Ni‑Co
• Quantities: prototype and/or production
• Surface finish and plating requirements (Ra, thickness, coverage/masking)
• Inspection and documentation needs (Ra data, XRF, C of C)
• Target timeline and application notes

KELTRYN helps engineering and sourcing teams turn Kovar designs into precision‑machined, production‑ready components—with surface finishing that supports hermetic sealing, plating adhesion, and repeatable performance.

RFQ Support

Send Your Kovar Machining RFQ

Share drawings, CAD files, material requirements, quantities, tolerances, finishing needs, inspection requirements, and your target timeline. Our team will review the details and respond by email.

Helpful RFQ details

2D drawings or 3D CAD files
Material: Kovar / ASTM F15 / Fe-Ni-Co alloy
Quantity, tolerance, finish, inspection needs
Application and purchasing timeline

Direct email: info@kovarmachining.com

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