Overview

A custom copper hermetic lid is a thin cover that seals a ceramic or metal package against moisture and gas, produced by photochemical machining rather than stamping. A photoresist mask is exposed with the lid outline and sealing-ring features, developed, and the unprotected copper is dissolved in a controlled cupric chloride or ferric chloride spray, so outline, seal-ring width and mounting-hole position are set by the artwork and etch time instead of die pressure. Typical stock is oxygen-free C1020 and C1100 copper between 0.15 mm and 0.80 mm, chosen for high thermal conductivity, easy brazing or welding and a ductile, clean sealing face that bonds reliably to ceramic and Kovar frames.

For semiconductor and RF packaging buyers, a custom copper hermetic lid solves three recurring problems: stamped covers carry burrs and bow that break the seal line and raise leak rates, the sealing ring must be flat to a few microns for a reliable braze or seam weld, and copper oxidizes so any heat tint or residue degrades plating and wettability. Chemical machining forms every feature on a sheet at the same rate, holding outline and ring flatness consistent from the first sample through volume production, while leaving the lid stress-free and ready for nickel or gold plating and hermetic sealing.

Parameter Window

• Available Materials: oxygen-free copper C1020, C1100 tough-pitch copper, copper-tungsten; also Kovar and 4J29 for mixed builds
• Material Thickness Range: 0.15–0.80 mm
• Tolerance: ±0.03 mm on outline, ±0.01 mm on seal-ring flatness
• Minimum Feature: 0.20 mm seal-ring width, 0.30 mm locating hole
• Surface Options: nickel or gold plating, anti-tarnish passivation, electropolishing, vacuum anneal, ultrasonic cleaning
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & Nesting — Convert the lid outline and seal-ring features to vector art, verify web rules, and lay out panels with shared fiducials.
2. Material Certification & Prep — Verify copper grade, mill certificate and thickness, inspect flatness and surface, then shear to exposure size.
3. Cleaning & Lamination — Degrease and laminate dry-film resist on both faces under matched heat and pressure without trapped bubbles.
4. UV Exposure — Expose the lid artwork through high-resolution film, registered to the sheet edge for panel-level outline accuracy.
5. Development — Wash out unexposed resist to open the feature areas and inspect for residue that would blunt the seal ring.
6. Controlled Etching — Spray copper-matched chemistry, tuning time, temperature and conveyor speed to hold ring width and avoid undercut.
7. Stripping & Plating — Strip resist, neutralize, then vacuum-anneal and apply nickel or gold plating for a wettable, oxidation-free seal face.
8. Inspection & Packaging — Measure outline, ring flatness and hole position on a vision system, verify leak-relevant flatness, then pack in clean trays.

Core Advantages

1. Burr-free seal line: Chemical removal leaves no rolled edge, so the lid seats flush on the package and the braze or weld line stays continuous.
2. No die cost: Each lid revision is a new film, keeping prototype packages and frequent outline changes economical without a blanking tool.
3. Flat sealing ring: The seal face holds ±0.01 mm flatness, which keeps leak rates low and braze wetting uniform around the whole perimeter.
4. Stress-free flatness: With no shear or heat input, the cover stays flat, so sealing, plating and thermal cycling will not bow the lid.
5. Conductor and heat spreader: Copper carries heat away from the die and accepts nickel or gold plating for corrosion protection and bonding.
6. Repeatable custom outlines: A custom copper hermetic lid can combine seal rings, windows and locating holes on one part, reproduced from first article to volume.

Typical Applications

• RF & microwave packages: Hermetic covers for power amplifiers and modules that need both sealing and heat spreading.
• Ceramic semiconductor packages: Lids brazed to ceramic or Kovar frames for MEMS, sensor and optoelectronic devices.
• Optoelectronic & laser housings: Moisture-tight covers for laser diodes, detectors and optical transceivers.
• MEMS cavity seals: Covers that protect sensitive moving structures from humidity and particles.
• High-power device lids: Copper covers that spread heat while maintaining a hermetic enclosure.
• Vacuum & sensor feedthrough covers: Seal plates for vacuum sensors and hermetic feedthrough assemblies.

Design Notes & Process Considerations

1. Ring-to-thickness ratio: Keep seal-ring width at or above roughly the sheet thickness; narrow rings in thick stock distort from undercut.
2. Flatness and leak callout: State seal-ring flatness, allowable bow and the target leak rate, since these set hermetic yield.
3. Grade and plating: Choose C1020 for brazing, and note nickel or gold plating thickness, because plating changes the final seal dimensions.
4. Joining method: Specify braze, solder or seam weld, and confirm the copper-to-frame material pair and thermal-expansion match.
5. Tie bars and borders: Leave adequate tie bars and process borders, and specify final singulation so thin rings survive stripping and plating.
6. Cleanliness and handling: With a custom copper hermetic lid, define plating coverage, residual-ion limits and clean-tray packaging for hermetic assembly.