1. High Power RF Capacitors There’s a Need ---
Now there’s a solution --- it’s about time!
Metal Clad and Mica Chips
When ceramics can’t handle the job

2. High Power RF Capacitors
SMT Metal Clad
Metal Clad Through-Hole
MC / MCN Mica Chips

3. It’s OK to Use Large Size Chips
Most companies restrict MLCC usage to 1206 or 1210
Large case MLCs (multi-layer chip sandwiches) film & mica are used--but not ceramic--at least not without special handling
Film chips up to size 6040 for modems and mica up to size 2220 for CATV have been commonly used for 10 years

4. Typical RF Filter Board broadband amplifier
Typical RF Filter Board broadband amplifier Watt mobile radio power board

5. RF Capacitors for High Power Applications
High Power…. Yes
Watts
Low Power…. NO

6. Metal Clad for Scorching Hot Applications
Lasers
Airborne
&
Mobile Radio
Manpack
Radio
MRI RF Coils

7. Benefits of Metal Clad Capacitors
Run Cool:
Silver plated brass cases and terminations
Like miniature heat sinks
Keep their cool by spreading heat
Carry High Current:
Ultra-high Q mica & TeflonÒ film dielectric
Generate very little internal heat

8. Benefits of Metal Clad Capacitors
Better than Ceramic:
TeflonÒ & mica rated 200ºC & No derating!
Overcome reluctance to use larger than 1210
Free from cracking or delamination
Don’t desolder like chips
Handle more current than capacitors up to twice their size

9. Metal Clad – Series Selection
Type MCM
Original Metal Clad Mica series
Low values TeflonÒ >8 pF uses mica
300, 500 and 1000 VDC
Wide temperature range –55 ºC to +200 ºC
Non-magnetic
Capacitance tolerance to ±0.25 pF
≈ 4640 & 5040 sizes

10. Metal Clad – Series Selection
Type MIN
MINiature metal clad series
All the features of original series MCM
300 VDC maximum
≈ 2220 EIA case size

11. Metal Clad & Mica Chips Similarities
Stable capacitance vs voltage, time, frequency
Exact values including non-standard ratings
Tight tolerance: chip ±0.1 pF, clad ±0.25 pF
Voltages 100 to 1000 Vdc
Relief from thermal cracking or delamination
Mica chips usually less expensive than metal clad

12. High RF Power Capacitor Features
Why use metal clad & mica chip power caps?
Handle the power / heat with a single capacitor.
Eliminate the need for farms of 1206 NPOs in parallel
Stable capacitance versus frequency, voltage, time
Nonmagnetic to minimize RF losses from eddy currents
Exact-value with non-standard ratings available
Tight tolerance chips to ±0.1 pF, metal clad to ±0.25pF

13. Mica Chips vs. Metal Clad - Differences
Metal clad spreads heat
Metal clad handles higher ripple currents
Metal clad rated to 200° C, chips to 125°C
Mica chips less expensive than metal clad
All metal clad series are nonmagnetic
Only type MCN mica chips are nonmagnetic

14. Competition for RF Power Capacitors
Porcelain and NPO MLCCs historically used for RF applications
1812, 1825 and 2225 EIA size MLCs are most common
NPO ceramic less costly than porcelain but --- cracking and delamination?
Competition
Areas of Weakness
ATC
Not in Digi-Key, Mouser catalogs for new designs
Very limited distribution
Chips may desolder with high power RF
Can’t handle same power as metal clad
Most series are magnetic.
Johanson

15. Market Info – High Power RF Power Caps
North American TAM RF Caps: $25+ million (est.)
CDE share ≈ 10% and rapidly growing
Porcelain and NPO best known RF power applications
CDE’s major competitors are weak in distribution
Major CDE customers: Motorola, Harris, E.F. Johnson
Better ASP & less competition than commodity products

16. News Release – ECN November 2005
CDE Cornell Dubilier has introduced high-power RF capacitors for military/aerospace and commercial radios and transmitters, CATV, automotive and medical RF generators and other applications requiring high-frequency operation into the low gigahertz and high-temperature operation up to 200°C. These capacitors are metal clad in silver plated metal cases to enable ultra-low inductance terminations and heat spreading for high power operation. The mica and Teflon® dielectric systems assure low ESR to greater than 1 GHz and high ripple current capabilities and stability in subminiature sizes. All styles are non-magnetic and are suitable for use in critical NMR MRI applications. Volume pricing for a 10 pF, ±0.5 pF unit is $0.39.

17. Applications for Metal Clad & Mica Chips
Communications
RF and microwave power amplifiers and transmitters
Mobile radio – typically 10 to 200 watts
Handheld, manpack, vehicular and base station radios
Airborne, ground, naval military & commercial radios
Telemetry
Wherever 1812, 1825, 2225 porcelain or NPO are used

18. Applications for Metal Clad & Mica Chips
Medical
RF coils for MRI
Electrosurgery & curettage
RF ablation (heart surgery)
CO2 lasers for cosmetic and optical
YAG lasers for skin and soft tissue

19. Applications for Metal Clad & Mica Chips
Industrial
CO2 & YAG lasers for industrial cutting
RF plasma generators for semiconductor fab
WLAN and WLL transmitters for WiMAX
Downhole logging – high temperature
Underhood automotive - high temperature
CATV repeaters exposed to lightning pulses

20. RF Capacitor Properties
DIELECTRIC
ADVANTAGES
DISADVANTAGES
Teflon
MIN
MCM
Metal clad resist desoldering
Lowest dielectric absorption (DA)
Very stable
Temperature rating to 200ºC
Low HF losses (low ESR & ESL)
More expensive than mica
Very limited values ≤33 pF
Wider Temperature coefficient
Mica
Extremely stable
Exact pF values, tight tolerances
Voltages to 1 kV
Temperature ratings to 200 ºC
Very high Q
DA not as low as Teflon®
Chips may desolder
continued

21. RF Capacitor Properties
DIELECTRIC
ADVANTAGES
DISADVANTAGES
NPO Ceramic
Very stable
High Q
Low inductance
Small sizes
Chips may desolder
Thermal shock, delamination
Exact values hard to get
Low power
Porcelain
Relatively expensive
Thermal shock / delamination

22. Part Numbering System

23. Definitions RF (Radio) Frequencies:
VHF (very high frequency) 30 MHz to 300 MHz
UHF (ultra high frequency) 300 MHz to 3 GHz
Q: Quality factor - capacitor merit. Inverse to DF
Very critical for RF applications to minimize distortion
Provides stability and long life
DF (dissipation factor): measure of the total AC resistances in a capacitor that causes power loss and capacitor heating

24. Definitions ESR (equivalent series resistance):
Resistance in capacitor plates and leads
Causes power loss as heat in high ripple, RF
ESL (equivalent series inductance):
Inductance in terminations, leads and capacitor plates
ESL can be a serious problem at high RF frequencies
Stacked vs. wound capacitors:
Insulation stacked in a multi-layer (MLC) sandwich
Most film and aluminum caps are rolled in a tube
MLC mica, film and ceramic preferred in RF apps

25. Definitions Stability:
Change in cap with change in time, frequency, voltage
Temperature Coefficient (TC):
Change in cap with temperature --- measured in ppm/°C
e.g., a 50 pF cap changes 0.5 pF (1%) from 25°C to 125°C
Formula for TC = ∆C x 106 ÷ C x ∆T = ppm/°C
TC = (125°C – 25°C) x 106 ÷ 50 pF x 100° = 100 ppm
Thus, a 100 ppm change, which is smaller than 1%

27. Contacts Commercial issues, price and delivery: Bea Gravelle
Technical information:
Bob Sevigny

28. Questions?

29. Thank You