RFI and EMI - Contacts, Fingerstock and Gaskets

Part Number	Description / PDF	Quantity
S7111-42R Harwin	RFI SHIELD FINGER AU 4.5MM SMD	10792
30302015 Würth Elektronik Midcom	GASKET FABRIC/FOAM 2MMX1M DSHAPE	978
07-0201-0237 Parker Chomerics	POLA SPONGE STRIP 11'X0.5X0.093"	23
38401201 Würth Elektronik Midcom	WE-EGS EMI ELASTOMER GASKET	12
3020503 Würth Elektronik Midcom	GASKET FABRIC/FOAM 5MMX1M RECT	1283
0077004102 Laird - Performance Materials	GASKET BECU 7.11X13.82MM	0
3029050030050 Würth Elektronik Midcom	WE-SMGS SURFACE MOUNT SOLDERABLE	2587
19-04-22371-S6305 Parker Chomerics	CHO-SEAL S6305 NI/C 0.043" 1'	419
3030806 Würth Elektronik Midcom	GASKET FABRIC/FOAM 8MMX1M DSHAPE	102
4906PA51H01800 Laird - Performance Materials	GSKT FAB/FOAM 4.8X457.2MM DSHAPE	0
4202PA51G01800 Laird - Performance Materials	GSKT FAB/FOAM 6.4X457.2MM DSHAPE	0
3851160 Würth Elektronik Midcom	WE-CSGS CONTACT SPRING GASKET	50
30395641 Würth Elektronik Midcom	WE-LT CONDUCTIVE SHIELDING GASKE	98
331265563040 Würth Elektronik Midcom	WE-SECF SMD EMI CONTACT FINGER 5	0
4080PA51H01800 Laird - Performance Materials	GASKET FAB/FOAM 22.9X457.2MM REC	0
3020707 Würth Elektronik Midcom	GASKET FABRIC/FOAM 7MMX1M SQ	0
4283PA22101800 Laird - Performance Materials	GASKET FAB/FOAM 4X457.2MM DSHAPE	0
3031018 Würth Elektronik Midcom	WE-LT CONDUCTIVE SHIELDING GASKE	19
1447009-5 TE Connectivity AMP Connectors	SHIELDFINGER0820TYPE	33054
55-54200 Parker Chomerics	FINGERSTOCK 0.08X0.25X16"	0

RFI and EMI - Contacts, Fingerstock and Gaskets

1. Overview

RF/IF (Radio Frequency/Intermediate Frequency) and RFID (Radio Frequency Identification) systems require effective electromagnetic interference (EMI) and radio frequency interference (RFI) shielding to maintain signal integrity. Contacts, fingerstock, and gaskets are critical components for ensuring electrical continuity and shielding performance in electronic enclosures. These components prevent electromagnetic leakage while maintaining mechanical functionality in connectors, housings, and assemblies.

2. Main Types and Functional Classification

Type	Functional Features	Application Examples
Contacts	Conductive elements for maintaining electrical connections under compression	RF connectors, PCB grounding pads
Fingerstock	Resilient metal strips with finger-like projections for continuous shielding	Server chassis, military equipment
Gaskets	Conductive elastomers or mesh materials for sealing gaps	Automotive sensors, medical devices

3. Structure and Composition

Typical structures include:

Contacts: Beryllium copper or phosphor bronze cores with conductive platings (gold, silver, nickel)
Fingerstock: Canted coil springs or stamped metal fingers with corrosion-resistant coatings
Gaskets: Silicone rubber with embedded silver-aluminum particles or wire mesh

4. Key Technical Parameters

Parameter	Typical Range	Significance
Contact Resistance	0.1-10 m	Affects signal transmission efficiency
Shielding Effectiveness	60-120 dB (100 MHz-10 GHz)	Determines EMI/RFI attenuation
Compression Force	0.5-5 N/mm	Impacts mechanical durability
Temperature Range	-55 C to +150 C	Defines operational stability

5. Application Fields

Main industries include:

Telecommunications (5G base stations, microwave links)
Automotive (V2X communication systems, radar sensors)
Aerospace (avionics shielding compartments)
Medical (MRI shielding enclosures)

6. Leading Manufacturers and Products

Manufacturer	Representative Products
Parker Chomerics	CHO-SEAL conductive gaskets
Laird Performance Materials	Form-in-Place EMI gaskets
3M	EMI Shielding Tapes 9703/9706
Samtec	RFI/EMI shielded connectors

7. Selection Recommendations

Considerations include:

Frequency range of the application (higher frequencies require tighter tolerances)
Environmental conditions (temperature, humidity, chemical exposure)
Material compatibility (avoid galvanic corrosion between mating surfaces)
Cost-effectiveness (balance performance vs. budget constraints)

Case Study: In automotive radar systems, Parker Chomerics' silicone-based gaskets reduced EMI leakage by 40% compared to traditional metal fingerstock.

8. Industry Trends

Key development directions:

Miniaturization for 5G mmWave applications
Low-PIM (Passive Intermodulation) material formulations
Multi-functional integration with thermal management
RoHS-compliant plating processes (eliminating hexavalent chromium)