PCBnew: I don't find the package of this common capacitor type

I don’t find this package. Is it named differently in PCBnew?
if yes: what’s the name please?
if not: I will design it.

That part info is pretty useless, and “CAP-SMD” is not a real package name.

Googling the part number gets me here: https://na.industrial.panasonic.com/products/capacitors/lineup/polymer-capacitors/series/79489/model/79572

which gives part dimensions as 7.3mm long x 4.3mm wide.

Even though it’s not actually a tantalum capacitor, it looks to be following the footprint size standard that tantalums use, so check in the Capacitor_Tantalum_SMD library. Tantalum cap footprint codes are 4 digits, LLWW, where LL and WW are the length and width in tenths of a mm. So we expect the footprint to be something like 7343.

Indeed there are several 7343 footprints in that library:

  • CP_EIA-7343-15_Kemet-W
  • CP_EIA-7343-20_Kemet-V
  • CP_EIA-7343-30_AVX-N
  • CP_EIA-7343-31_Kemet-D
  • CP_EIA-7343-40_Kemet-Y
  • CP_EIA-7343-43_Kemet-X

plus their handsoldering variants with slightly larger pads. The last number in each of those footprint names is the height of the package, which affects the 3D model but not the copper.

You can check those footprints to see if they are compatible with the part and footprint dimensions given in the datasheet. I didn’t check carefully, but they seem to be similar but not identical to what Panasonic recommends.


It’s a L7.3 x W4.3 x H1.9 smd capacitor

cross posting :grinning:

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Thank you so much. Very helpful explanation and indeed I found the shape.

Just for completion for my knowledge please: what the last letter “W”, “V”, “D”, “X”, “Y”, stands for?

Thank you again

It’s the providers size designation

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I have not checked whether multiple manufacturers use the same package size designations. This datasheet covers some tantalum polymer which are somewhat expensive. Depending on what you need, you might be better off with aluminum polymer or aluminum electrolytics. The aluminum polymer are also available in radial leaded cans and SMT cans.

BEWARE of one issue with all tantalum capacitors (SFAIK). While aluminum electrolytics have a cathode band marking, tantalum capacitors have an anode band marking. In recent years there have been (I think) at least a couple of high profile product recalls because tantalum capacitors (or tantalum polymer capacitors) were installed backwards and catching fire. Does anyone know how it came to be that the two capacitor types ended up with reversed markings? It is a legacy issue; I think for as long as tantalum and aluminum electrolytic capacitors have been around.


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Just a guess, but very early THT radial tantalums were packaged in a similar way to radial electrolytics. Many of both types had printing on the can, often covered in clear shrink-wrap (I still have a few pieces of that history). A + at the anode instead of a black band at the cathode was really the only way to tell the difference sometimes.

Now that you mention it, it’s true, the electrolytic capacitors in my junk^Wspares box have either a cathode stripe or a band, while the bead tantalums have an anode mark. I suppose it makes a point of difference between the two types. I prefer it this way. Hand assemblers who don’t look deserve what they get. (Including me the last time I installed a couple of crystal load capacitors perpendicular to the correct orientation, ignoring the silkscreen footprint lines.)

The capacitor is Aluminium Electrolytic.
It’s not tantalum


It gets complicated. That is an aluminum polymer…not properly called an aluminum electrolytic. Aluminum polymers (and tantalum polymers) both generally have lower equivalent series resistance than most “electrolytic” capacitors. When those were introduced, Panasonic called them Polymer Function Capacitors. I guess that is better than calling them Malfunction capacitors. :laughing:

For further confusion, refer to Os-Con capacitors which type was introduced by Sanyo maybe 25 years ago but is now owned by Panasonic.

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If someone were going to accidentally put in an aluminum (polymer or electrolytic) instead of a tantalum (polymer or electrolytic) or vice versa, that might work passably if the voltage and polarity is correct. But if the capacitor is reversed, then really the question is how bad the result will be; not whether the result is bad. Failed tantalums can sometimes catch fire if enough power is available, and vented aluminum electrolytics stink badly; a bit like rotten fish.

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That’s a tantalising prospect. :stuck_out_tongue_winking_eye:

I will stick to oatmeal.

When there were problems with tantalum capacitors availability (I think it was in 2002 - earthquake) I moved to ceramics. Those time their producers argued that 2u2 ceramic can replace 4u7 tantalum (because of lower ESR). I never went back to tantalums. I have read that many of ceramics are tested with 2.5 times higher voltage than nominal (may be not the biggest capacitances in smallest packages) and tantalum capacitors you should use at 1/2 of their nominal voltage as even small overvoltage can result in fire. At first I used 22uF Y5V but since many years I use only X7R and X5R. 22uF/6V3 or 22uF/10V are 0805 size. Bigger capacitance is also available.
By the way I got zero problems when capacitor is reversed :slight_smile:

HiK types like Z5U and even X7R lose capacitance badly as you approach rated voltage

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I use 6V3 capacitors at 3V3 and 10V at 5V. So the capacitance lose is about 15% I think. I don’t check it now in datasheet.

Capacitance loss can be 60% or more at half the rated voltage, and varies dramatically by part even with the same dielectric and manufacturer. Generally, bigger packages have less capacitance loss, and manufacturers don’t like putting the dc bias chart in datasheets (they often have additional per-product characteristic sheets for this).

As an example, here’s a fairly typical 10V rated 0603-sized X5R cap’s characteristic sheet: you can see it loses 80% of its capacitance at 5V bias. https://product.tdk.com/system/files/dam/doc/product/capacitor/ceramic/mlcc/charasheet/c1608x5r1a226m080ac_200817.pdf

I’m shocked. Good to know.
I just supposed (was pretty sure) that it is a question of field strength. As the breaking voltage is (in my opinion) also a question of field strength so both should be correlated in that way that capacitance lost in % should depend only on dielectric and % of nominal voltage.
I based on Hitano hart showing for X5R about 40% capacitance lost for 100% of nominal voltage (and 15% for 50% of voltage).
The shape like in your link (70% lose) has a Hitano chart for Y5V capacitors.
I supposed that not using Y5V I have no this problem as high as you show.

Like I said, it varies dramatically by part even with the same dielectric and same manufacturer. For parts where the capacitance is critical you need to check every part. I usually use larger package sizes because the effect is worse for smaller parts.