One-piece vs two-piece shields?

One-piece: stamped metal can soldered over components. Lowest cost but must be desoldered for rework. Two-piece: a fence (frame) soldered permanently to the board, plus a removable lid that clips on. The lid can be removed for testing and rework without desoldering. Two-piece adds $0.10-0.50 but saves significant rework cost.

Design considerations?

Continuous ground pad (0.5-1.0 mm wide) around the shield perimeter for solder attachment. Ground vias every 2-3 mm along the pad for connection to inner ground planes. Height clearance: 1.0-4.0 mm typical, must clear tallest component plus 0.3 mm minimum. Internal compartments isolate different frequency sections (e.g., TX and RX in a radio module).

Manufacturing

Board-Level Shield

Q: Shielding effectiveness?

Typical board-level shields provide 20-40 dB at 1-3 GHz, increasing to 40-60 dB at lower frequencies. Effectiveness depends on material thickness (0.15-0.3 mm steel or nickel silver), solder joint quality, and aperture control. Openings for ventilation or connectors degrade shielding. Each slot acts as a slot antenna: SE (dB) decreases as slot length approaches lambda/2.

A Board-Level Shield (BLS) is a stamped or drawn metal enclosure (0.15-0.3 mm thick steel, nickel silver, or mu-metal) soldered directly onto a PCB over sensitive or noisy components. It provides 20-60 dB of electromagnetic isolation at the component level, enabling compact multi-radio designs (Wi-Fi + Bluetooth + cellular) on a single board without mutual interference. Two-piece designs (permanent fence + removable lid) allow rework access without desoldering.

Category: Manufacturing

SE: 20-60 dB

Understanding Board-Level Shields

BLS is standard practice in smartphones, wireless modules, and IoT gateways where multiple radios share a small PCB. Without shielding, a Bluetooth radio's harmonics can desensitize a nearby GPS receiver by 10-20 dB. A BLS over the Bluetooth section contains its emissions, and a BLS over the GPS section improves its immunity.

The PCB ground pad must be continuous around the shield perimeter with ground vias every 2-3 mm connecting to inner ground planes. Gaps in the solder joint or missing vias create slots that leak RF energy, degrading shielding effectiveness above the slot's resonant frequency.

Slot Leakage

Max slot length for target SE:
L_slot < λ/2 at highest frequency

At 6 GHz (λ=50 mm):
Max slot = 25 mm
Via spacing: ≤2.5 mm (λ/20 rule)

Shield Type Comparison

Type	Cost	Rework	SE	Height
One-piece can	$0.05-0.30	Desolder	20-40 dB	1-4 mm
Two-piece	$0.15-0.80	Clip-off lid	20-40 dB	1-4 mm
Compartmented	$0.30-1.50	Per section	30-50 dB	2-5 mm
Custom drawn	$0.50-3.00	Varies	40-60 dB	Custom

Common Questions

Frequently Asked Questions

One vs two piece?

One-piece: cheapest, must desolder for rework. Two-piece: fence + clip-on lid, rework-friendly, $0.10-0.50 more.

Effectiveness?

20-40 dB typical at 1-3 GHz. Depends on material, solder joints, and apertures. Slots degrade SE above their resonance.

Design rules?

0.5-1 mm ground pad, vias every 2-3 mm, 0.3 mm component clearance. Internal walls for multi-radio isolation.

Related Terms

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EMI Shielding

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