Over and over again the question comes up, “How long is the MLCC shortage going to continue?” The general consensus in the industry is that this will continue through 2020. In the meantime, KEMET’s KO-CAP polymer electrolytic capacitors are available to offer some relief. There are several design considerations that must be taken into account when determining to make the switch.
The Benefits of Polymer
KO-CAP is a tantalum-based polymer electrolytic capacitor. Like traditional tantalum capacitors, KO-CAP has an anode that is a sintered slug of tantalum powder with an oxide dielectric. That’s where the similarities end. The cathode is a conductive polymer. This conductive polymer material has much lower resistivity than manganese dioxide, which is what is used in legacy tantalum capacitors.
Features & Benefits
-- High volumetric efficiency
-- Low ESR
-- Stable frequency response
-- Stable temperature profile
-- Stable across voltage
-- No piezoelectric noise
When caught up in an MLCC supply shortage, making the switch over to KO-CAP is not trivial. A switch is only possible when the parameters of KO-CAP intersect with the design requirements.
Making the Change
There are several factors that must be considered when making the switch over to KO-CAP.
-- Total required capacitance: Must be greater than 680nF for KO-CAP to be considered
-- Application Voltage: Must be less than or equal to 50V
-- ESR: 4 to 8 milliohms are the lowest
-- Frequency: Best suited for switching frequencies less than 1MHz
-- Reverse bias: Must not see reverse bias voltage
If all of these factors are suitable for the design conditions, then migrating to KO-CAP is an option.
The Value Proposition
It may seem like a challenging design change to go from MLCC to polymer, but in the cases where a bank of MLCCs is replaced with one KO-CAP, it becomes a compelling change. Sometimes MLCCs are the only option, but when the design requirements allow for it, switching to KO-CAP may well be worth the design change.
These benefits include:
-- Reduced BOM count
-- Lower total capacitance cost
-- Reduced board area
-- Electrical stability
In addition to these benefits, the tantalum supply chain is currently stable and KEMET is adding more capacity. When there are no other MLCC options available, consider KO-CAP and perhaps find some relief in this MLCC capacity crunch.
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