How to Read Aluminum Electrolytic and Tantalum Capacitor Markings — 107 · 227 A codes, polarity bands (opposite!), UVR1A332MHD · TAJC106M035RNJ part numbers

Figure description: At the counter of an electronic parts shop, a customer holds up a yellow tantalum chip with tweezers. One end of the chip has a brown band, and 107 D is printed on top. On the counter lies a cylindrical aluminum electrolytic capacitor with a minus stripe on its side. The customer asks, “The side with the band is minus, right?” A female clerk in a red apron points at the brown band and answers, “On tantalum, the band is plus (+)!”

Aluminum electrolytic capacitors and tantalum capacitors are both polarized (+ · −) capacitors. The printed markings are short, but the pole the band indicates and the way the numbers are read differ between them, so reading both the same way easily leads to mistakes. This article covers body markings and then ordering part numbers, in that order.

All values were checked against the manufacturers' datasheets (Nichicon · KYOCERA AVX · KEMET). Click a part number to look up stock in eGuro Part Search.

1. Polarity first — the band means opposite things

This is the most important difference. On aluminum electrolytics the band side is −, but on tantalum the band side is +. The AVX datasheet labels the band 'Polarity Band (Anode+)', and KEMET labels it 'Polarity Indicator (+)'. On chip aluminum electrolytics, the black-colored side of the top is −. Polarized capacitors can be destroyed if mounted backwards, so always match the + mark on the board with the marking on the part.

2. Aluminum electrolytic body markings

Leaded types print the capacitance (µF) and voltage (V) as is, in white text on a black sleeve. Chip types also print the µF number as is on top, such as 10, and according to the Nichicon UWT datasheet 6.3V is printed as '6V'. Don't mistake a chip marked 6V for a 6V part. Other text such as the company mark and the production lot number is printed as well.

3. Tantalum body markings (107 · 227 A)

The three digits on a tantalum chip are a pF (picofarad) code. The first two digits are the figures, and the third digit is the number of zeros that follow. So 107 is not 107µF but 100µF (10 followed by 7 zeros = 100,000,000pF = 100µF). AVX prints a voltage letter next to it — the datasheet example gives A = 10V, J = 6.3V; check other letters in that manufacturer's datasheet table. KEMET T491 prints the + mark, rated voltage, pF code, KEMET ID and a date code (first digit = last digit of the year, second and third = week of that year).

Figure description: Holding a yellow tantalum chip marked 107 in one hand and an aluminum electrolytic capacitor marked 100µF 16V in the other, a confused customer asks, “If it says 107, is it 107µF?” A female clerk writes ‘10 + 0000000pF = 100µF’ on a memo pad, shows it and answers, “It's 100µF! Tantalum 107 is a pF code.”

4. Aluminum electrolytic part numbers (UVR1A332MHD)

Aluminum electrolytic part numbers from Japanese manufacturers such as Nichicon write the voltage as a two-character digit+letter code (1A = 10V, 1C = 16V, 1H = 50V …). Capacitance is a three-digit code, but the unit is µF: in UVR1A332MHD, 332 is 33 × 10² = 3300µF; in UVR1C101MPD, 101 is 100µF. Even with the same three digits, the unit differs from the pF code on tantalum chips, so take care. The voltage codes above are from the tables in the Nichicon UVR·UWT datasheets (0G is UWT).

5. Tantalum part numbers (TAJC106M035RNJ · T491X157K020AT)

In both companies' tantalum part numbers, capacitance is a pF code and voltage is three digits (016 = 16V, 035 = 35V). TAJC106M035RNJ is TAJ · C case · 10µF · ±20% · 35V · 7-inch reel, and T491X157K020AT is T491 · X case · 150µF · ±10% · 20V.

6. Tantalum case letters — differ by manufacturer

Tantalum cases are called by letters such as A · B · C · D, but only A~D and S · T are the same at both companies; for the rest, the same letter refers to a different size. For example, a 7.3 × 4.3mm chip with a height of 4.3mm is E at AVX and X at KEMET, while AVX's X is a thin chip with a height of 1.5mm. When switching to another company's part number, compare by EIA size, not by case letter. How to read package sizes is covered in the Component Package Names: A Complete Guide article.
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7. The most confusing traps

• The band means the opposite — on aluminum electrolytics the band side is −, on tantalum the band side is +
• Unit of the three digits — tantalum body and part number (107) are a pF code = 100µF, Nichicon aluminum part numbers (101) are a µF code = 100µF, aluminum bodies (100) are µF as is
• 6V means 6.3V — chip aluminum electrolytics print 6.3V as 6V
• How voltage is written — on the body as a letter (A = 10V) or number+V; in part numbers as 1A (Nichicon) or 010 (AVX · KEMET)
• Case letters — E · U · V · W · X · Y are different sizes at AVX and KEMET

8. What to check when quoting or substituting

• Capacitance and tolerance — check the code unit (pF · µF) first
• Rated voltage — equal to or higher than the original part
• Polarity and size — diameter × length (φD × L) for leaded types, EIA size for chip types
• Temperature — differs by series even among aluminum electrolytics, e.g. UVR −40~85℃, UWT −55~105℃
• Packaging — whether everything matches down to the last characters, such as 7-inch · 13-inch reel

Sources: Type numbering system · How to Order · Ordering Information · Marking · case dimension tables in the datasheets for Nichicon UVR (CAT.8100M) · UWT (CAT.8100N), KYOCERA AVX TAJ and KEMET T491 (T2005_T491). Markings and codes may differ by manufacturer and series, so check the relevant datasheet before placing an actual order.