Guidelines for Handling PolyStrata® Components

This document provides guidance on how to handle, store, and assemble PolyStrata® components. PolyStrata® parts are high‑performance components that can be handled and assembled using standard microelectronics industry methods.

Part Finish

• PolyStrata® components are constructed from high‑purity electroplated copper, with several available surface finishes.
• Bare Copper (BCU): no surface finish applied; compatible with solder surface‑mount processes.
• Direct Immersion Gold (DIG): minimum 100nm immersion gold; compatible with solder and epoxy surface‑mount processes, and gold wire bonding.

General Handling & Storage

PolyStrata® components are not ESD sensitive.

Handling

• Components are solid‑state RF devices using air as a dielectric; the most sensitive cavities/surfaces sit inside a robust copper ground shell, so exterior scratches or surface defects generally don’t affect performance.
• Avoid bending or deforming parts — copper deforms under excessive force and may detune interior structures.
• Some designs place sensitive features at the extents of the part due to interconnect requirements.
• Vacuum pick tools are recommended. Designated pick‑up areas will be provided. Limit placement force to <400 grams.

Storage

• Inhibiting corrosion is the primary storage objective.
• DIG parts should avoid exposure to sulfur or chloride‑containing substances.
• Do not store with desiccant in the same bag as the part — this can cause tarnish. Bag & seal parts first, then place in a secondary bag with desiccant.

In‑Process Storage

• BCU finished parts: handle as MSL5 per J‑STD‑033.
• DIG finished parts: handle as MSL2a per J‑STD‑033.

Long‑Term Storage

• No risk of popcorning or delamination — no plastic molding or lamination is used. Parts are rated MSL1.
• As solid‑state RF devices, long‑term storage should follow JEDEC JEP160 guidance for oxygen‑sensitive devices.

FOD Sensitivity

PolyStrata® parts have 250–500µm openings to interior RF cavities. A conductive or non‑conductive particle lodged inside can detune or short the device. Standard cleanliness and FOD control procedures are sufficient until the part is enclosed
in a dust‑proof housing.

N₂ or inert gas environments are recommended (not required) for elevated‑temperature
processes such as epoxy cures or solder reflow.

Solder Reflow

• Compatible with all solder reflow profiles described in J‑STD‑020.
• DIG finished parts are protected against reflow‑interfering corrosion and have passed MSL1 testing.
• BCU finished parts will form visible purple copper oxides over time. If storage precautions are followed, standard flux action during reflow is typically enough to clean and prepare the surface. If needed, a spray/dip clean with acetic acid, isopropyl rinse, and thorough drying removes the oxide.

Epoxy

• BCU finished parts are not recommended for silver‑filled conductive epoxy attach — the copper surface is generally incompatible with available epoxies.
• DIG finished parts are preferred for silver‑filled conductive epoxies.

Die Attach

• Silver Sintered Nano Particle paste is recommended for bare die attach. Confirm compatibility with your surface finish with the material vendor.

Wire Bonding

• DIG finished parts support gold ribbon, wire, and ball bonding. Use Argon plasma cleaning immediately before bonding — do not use oxygen plasma.
• Secure parts firmly during heated‑stage bonding; account for part shape and bottom‑surface geometry.
• Parts remain wire‑bondable after multiple thermal excursions through solder reflow (6 min @ 260°C) or ambient exposure, with bond strengths exceeding MIL‑STD‑883 pull‑test requirements (with Argon plasma clean prior to bonding).

Cleaning

• Compatible with a wide range of solvents: isopropyl, acetic acid, hydrofluoric acid, and various flux cleaners.
• Wash temperatures up to 70°C are acceptable.
• A final isopropyl rinse and dry bake in nitrogen is recommended to remove any residual chemistry or moisture.
• Ultrasonic cleaning may fatigue small suspended internal structures and permanently damage RF features (sensitivity can be assessed per part via FEA).
• Watch for FOD: loose conductive or non‑conductive particles (~50–250µm) in solutions or on devices can enter and lodge in the RF interior, causing detuning or shorts.

Typical Environmental Test Results