Feed Through Capacitors

Part Number	Description / PDF	Quantity
B85321A2205A101 TDK EPCOS	FILTER 1UF TH	5
B85321A2502Z160 TDK EPCOS	FILTER LC (PI) 2500PF TH	10
B85321A2205A250 TDK EPCOS	FILTER 1UF TH	10
B85321A2205A401 TDK EPCOS	CAP FEEDTHRU	4
B85321A2205A630 TDK EPCOS	FILTER LC(PI) 1UF TH	6
B85321A2502W160 TDK EPCOS	FILTER 2500PF TH	812
B85321A2105A301 TDK EPCOS	CAP FEEDTHRU	0
B85321A2405A201 TDK EPCOS	CAP FEEDTHRU	0
B85321A2945A401 TDK EPCOS	CAP FEEDTHRU	0
B85321A2105A101 TDK EPCOS	CAP FEEDTHRU	0
B85321A2502X160 TDK EPCOS	CAP FEEDTHRU	0
B85321A2204A750 TDK EPCOS	CAP FEEDTHRU	0
B85321A2105A630 TDK EPCOS	CAP FEEDTHRU	0
B85321A2205A750 TDK EPCOS	CAP FEEDTHRU	16
B85321A2405A401 TDK EPCOS	CAP FEEDTHRU	0
B85321A2205A201 TDK EPCOS	CAP FEEDTHRU	0
B85321A2205A301 TDK EPCOS	CAP FEEDTHRU	0
B85321A2405A101 TDK EPCOS	CAP FEEDTHRU	4
B85321A2204A250 TDK EPCOS	CAP FEEDTHRU	0
B85321A2105A201 TDK EPCOS	CAP FEEDTHRU	0

Feed Through Capacitors

1. Overview

Feed Through Capacitors are specialized passive components designed to suppress high-frequency noise in electronic circuits while allowing DC or low-frequency signals to pass through. They act as electromagnetic interference (EMI) filters by providing a low-impedance path to ground for unwanted high-frequency signals. These capacitors are critical in ensuring signal integrity and compliance with electromagnetic compatibility (EMC) standards across industries such as aerospace, medical devices, and telecommunications.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
Ceramic Feed Through Capacitors	High dielectric constant, compact size, wide frequency range (up to GHz)	RF amplifiers, mobile devices
Film Feed Through Capacitors	Self-healing properties, low dielectric loss	Power supplies, industrial motors
Three-Terminal Capacitors	Reduced equivalent series inductance (ESL), improved high-frequency performance	High-speed digital circuits
Multi-Core Feed Through Capacitors	Integrated multiple capacitors in a single package	Medical imaging equipment

3. Structure and Composition

A typical Feed Through Capacitor features a cylindrical ceramic or polymer dielectric body with three terminals: input, output, and ground. The internal structure includes concentric conductive layers separated by dielectric materials. Advanced designs incorporate multi-layer ceramic (MLCC) technology or wound film structures. Key components include:

Dielectric material (e.g., X7R ceramic, polypropylene)
Conductive electrodes (silver, copper, or aluminum)
Hermetically sealed housing for environmental protection
Gold-plated or tin-coated terminals for connectivity

4. Key Technical Specifications

Parameter	Typical Range	Importance
Capacitance	100 pF - 100 F	Determines noise filtering effectiveness
Voltage Rating	50V - 3kV	Ensures safe operation under load
Frequency Range	1 MHz - 10 GHz	Defines applicable signal bandwidth
Insulation Resistance	>10,000 M	Prevents leakage currents
Operating Temperature	-55 C to +150 C	Affects reliability in extreme conditions

5. Application Fields

Key industries and equipment:

Medical: MRI machines, pacemakers, ultrasound scanners
Telecommunications: 5G base stations, satellite transponders
Industrial: CNC machine controllers, motor drives
Aerospace: Avionics systems, radar equipment

Case Study: In MRI systems, Feed Through Capacitors enable artifact-free imaging by eliminating RF interference in gradient coil drivers.

6. Leading Manufacturers and Products

Manufacturer	Product Series	Technical Advantages
Murata	NFM21CC Series	Ultra-low ESL (0.1 nH), 100 MHz - 3 GHz operation
TDK	B32920 Series	High voltage tolerance (2500V), flame-retardant housing
Kemet	CPR21FP Series	Space-grade reliability, operating temp -65 C to +200 C

7. Selection Guidelines

Key considerations:

Determine required capacitance range based on noise frequency spectrum
Select voltage rating exceeding maximum system voltage by 20%
Evaluate thermal management needs for high-current applications
Consider package size constraints (e.g., 0603 vs. 1812)
Verify compliance with standards (e.g., IEC 60384-14)

8. Industry Trends

Future developments include:

Miniaturization: Sub-0402 packages for wearable devices
High-Frequency Optimization: 10+ GHz performance for 6G infrastructure
Integration: System-in-Package (SiP) solutions with embedded filters
Environmental Durability: Automotive-grade capacitors for 150 C+ operation
Material Innovation: Barium titanate nanocomposites for higher capacitance density