How to Order Kemet Tantalum Capacitors Without Costly Mistakes: A 5-Step Checklist

Who This Checklist Is For

If you're ordering Kemet tantalum capacitors for the first time—or even if you've done it a dozen times—this checklist is for you. I've made enough mistakes in my 7 years sourcing passive components that I now maintain a team checklist so others don't repeat them. My experience is based on roughly 180 mid- to high-reliability orders, mostly for industrial and medical applications. If you're working with ultra-low-cost consumer gear, your mileage might vary.

Step 1: Verify the Part Number Against the Official Datasheet

In my first year (2018), I ordered 500 pcs of Kemet T494A106K010AT—or rather, I thought I did. The supplier sent T494A106K010AS. Same package, same ratings, but the 'S' suffix meant a different solder coating. That mistake cost $340 in rework plus a two-week delay.

What I mean is: always cross-check the full part number on Kemet's official site (kemet.com). Don't trust the supplier's auto-fill. Write it down yourself, then verify each character. Pay special attention to suffixes for packaging, termination, and voltage rating.

Check point: Have you looked at the datasheet PDF within the last 6 months? Part obsolescence happens (ugh).

Step 2: Confirm Voltage Derating Requirements (Especially for Medical Devices)

Here's the thing most beginners miss: a 10V tantalum capacitor rated for general use might fail in a blood pressure monitor if it's run at 8V continuously. I've seen this first-hand—well, actually I caused it once. In September 2022, I approved a design using Kemet T491 series at 80% rated voltage. The monitor passed initial tests, but after 500 hours in a 40°C chamber, two capacitors shorted. That recall cost us roughly $4,200.

The lesson: for medical applications (where you see those blood pressure monitor symbols like BP and mmHg on the schematic), derate to 50% of rated voltage. For industrial use, 70% is safe. Write the derating factor into your spec sheet—don't trust memory.

Step 3: Choose the Right Distributor (and Check Their Authorization)

I once ordered 1,000 Kemet T491D107M016AT from an online marketplace for $0.18 each—a great price. They were counterfeit. The tabs were wrong, capacitance drifted, and we caught it when the HPE server power supply oscillated (fun times). $180 down the drain plus testing fees. Now I only buy from authorized Kemet distributors. The list is on Kemet's website—there are about 15 globally.

[This is a good time to mention that official Kemet distributors often offer technical support and batch traceability. The total cost of a fake part can easily exceed the price difference.]

Step 4: Calculate Total Cost of Ownership (TCO) for the Batch

The $0.50 part from Distributor A might seem cheaper than $0.55 from Distributor B. But did you factor in:

• Shipping: Distributor A charges $15 flat, B ships free over $200.
• Minimum order: A requires 500 pcs, you need 400. That's 100 extra parts (waste).
• Lead time: A ships in 10 days, but you need 3-day rush (+40% premium).
• Risk: B has been your supplier for 5 years—zero counterfeit issues.

The $500 quote from A turned into $820 after rush fees and wasted inventory. The $550 from B was actually cheaper. I now run a simple spreadsheet for every order over $200. (Not that my team always remembers—hence this checklist.)

Step 5: Test with a Known Good Multimeter Before Assembly

This sounds obvious, but you'd be surprised how many people skip it. Get yourself a decent multimeter—the best multimeter for capacitor testing is one that measures capacitance and ESR (e.g., Fluke 117 or Keysight U1233A). For Kemet tantalums, I check:

• Capacitance at 1kHz: should be within ±20% of rated value.
• ESR: typically < 1Ω for small values, < 0.5Ω for larger.
• Leakage current: apply rated voltage for 5 minutes, measure leakage. (Expect < 0.5μA for parts under 10μF.)

In 2023, I tested a batch of 200 Kemet T491C476K016AT and found five with leakage > 2μA. Sent them back, saved a board-level failure (probably worth $600+). The multimeter paid for itself in one afternoon.

Common Mistakes I've Seen (and Made)

1. Ignoring polarity marks

Some engineers confuse the tantalum capacitor's polarity stripe with a blood pressure monitor symbol (yes, I've seen that). Always verify the orientation: the stripe on Kemet tantalums indicates the positive terminal. On aluminum electrolytics it's negative—don't mix them up. (Ugh.)

2. Assuming all Kemet distributors offer the same warranty

Some authorized distributors provide a 1-year return window; others only 30 days. Always check the terms. One small startup ordered from a distributor that required RMA within 14 days; by the time they tested the parts, it was too late. $900 frozen in inventory.

3. Overlooking RoHS and REACH compliance declarations

If your product ships to Europe, you need documentation. I once had to re-certify an entire HPE-compatible power supply because the certificate from the distributor didn't cover a specific batch code. The paperwork delay cost us a quarter's shipment.

Bottom Line

This checklist isn't perfect—I'm constantly updating it. If you're ordering Kemet tantalum capacitors for a project, at least run through steps 1–5. It takes 20 minutes and could save you thousands. (It saved me about $5,000 last year alone.) The best multimeter I own is still the one I use to spot-check every incoming batch. And remember: the cheapest part is rarely the cheapest when you add up the headaches.