PASSIVE
MLCCs replacing aluminium and tantalum capacitors
the IncredIble Increase In Mlcc caPacItance values has resulted In the rePlaceMent of aluMInIuM and tantaluM caPacItors
Since 1970 the capacity of aluminium capacitors, at the same voltage rating (C/V value), has increased by approximately 10 times and 20 times for tantalum capacitors. However, for MLCCs this increase has been much larger, approximately 500 times. This explains why aluminium and tantalum capacitors are being increasingly replaced by MLCCs. Additionally there are other advantages to using MLCCs from Samsung Electro- Mechanics (SEMCO). MLCCs are manufactured as surface mount devices only, in very high
production volumes. This makes production, handling and processing very efficient. The production capacity, especially for ultra high capacitance values, has increased dramatically at SEMCO. For MLCCs, production capacity has increased by 350% in 3 years. In contrast the production capacity of aluminium and tantalum capacitors has remained stable. The replacement process for an aluminium or tantalum portfolio will always start with low C/V rating types, continuing up to high C/V ratings. Depending on the application conditions, class 2 type MLCCs, with X5R (85°
C) or X7R (125° C), are recommended. The electrical parameters
require closer inspection as they differ from aluminium and tantalum capacitors, especially the DC-bias effect of class 2 type MLCCs. The high k di-electric material used in class 2 MLCCs is a piezo electric material. Due to this, the real capacitance value is reduced with increased DC voltage. Depending on the DC voltage, an MLCC with a higher nominal capacitance value needs to be chosen in comparison with aluminium or tantalum capacitors. However, there are several advantages of MLCCs as shown in the table (right).
The highest capacitance values are available with the X5R series. SEMCO was the first company to introduce 100µF/10V in a package size of 1210. At a DC-voltage level of 5.5V this type can replace 50µF/10V aluminium capacitors and 50µF/30V tantalum capacitors. Also at higher voltage ratings SEMCO can offer high capacitance values, e.g. 22µF/25V
or 10µF/50V in a package size of 1206. All these MLCCs save more than 2/3 of the space of the PCB surface compared to equivalent auminium or tantalum caps.
For higher temperature ratings up to +125° C SEMCO offers its X7R
series MLCC. In mass production the maximum nominal capacitance for 10V types is currently 47µF for a size of 1210 and 22µ for a size of1206. These are ideal for more severe applications in industrial environments.
Also, the mechanical strength of MLCCs is excellent. In the past MLCCs suffered problems due to cracks from bending or thermal shock. Nowadays SEMCO can offer soft terminations for class 2 ceramics. Board flex tests for standard parts show the first cracks appear after 2mm of bending for the large case sizes. SEMCO’s silver-epoxy soft termination is placed between the outer nickel plating and the inner copper termination and it absorbs the mechanical stress and improves class 2 MLCC bending strength to 5mm with no cracks occurring.
AL Performance Polarity Down-sizing ESR/ESL
Ripple current & self heating Surge/withstanding voltage Insulation resistance DC/AC bias
Distortion/acoustic noise
Polar Poor
Frequency dependency, noise absorption (wide frequency range) Poor
Poor Poor
Good Poor
Good Good
Tantalum MLCC
Electrolytic Capacitor (Class II, X5R/X7R)
Polar Good
Poor Poor
Good Poor Poor
Good Good
Non-Polar Excellent
Excellent Excellent
Excellent Excellent Good Poor Poor
Replacement of aluminium and tantalum capacitors with X5R and X7R MLCCs still needs evaluating on a case by case basis but the pay off of space saving, lower ripple current, higher withstanding voltages and a longer lifetime make it worth a closer look.
related Products: » 1210, X5R, 100µF, 20%, 10V – CL32A107MPVNNNE » 1206, X5R, 22µF, 10%, 25V – CL31A226KAHNNNE » 1206, X5R, 10µF, 10%, 50V – CL31A106KBHNNNE » 1210, X7R, 47µF, 10%, 10V – CL32B476MPJNNNE » 1206, X7R, 22µF, 10%, 10V – CL31B226KPHNNNE
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www.avnet-abacus.eu/samsungMLCC to download our new SEMCO MLCC brochure » » »
14 focus magazine - issue 9
www.avnet-abacus.eu
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