Let me start with the honest part: there is no universal answer for which KEMET part to pick. I manage component sourcing at a 300-person electronics company. My annual budget for passive components, relays, connectors, and related parts is about $1.8 million, and I have tracked every order in a cost system since 2017. That tracking changed my opinion on cheap suppliers. It also taught me to question my first answer.
In my first year, I made the classic rookie mistake: I compared only unit prices. A connector with the same pin count and pitch cost 20% less than the approved one. It looked identical, until I missed the lock mechanism detail. During the customer vibration test, the connector let go. The rework plus expedited freight cost about $1,400, and we still missed the ship date.
Since then I have used a scenario framework. The right component depends on volume, failure cost, and product lifecycle. Let me walk through it.
A quick search detour before the scenarios
Search terms can be messy. Some of you typed ‘Kemet relays,’ some typed ‘connectors,’ and a few may have typed ‘Kemet lapping.’ The KEMET I discuss in this article is KEMET Electronics, the company that designs and sells ceramic capacitors, tantalum capacitors, MLCCs, relays, and connectors. The Kemet term that appears next to lapping is usually a different company, Kemet International Ltd, which makes lapping and polishing equipment. This guide is about the electronics side.
Another phrase that shows up in site analytics is ‘how to use blood pressure monitor.’ If you need standard operating instructions, the manual is the right source. But if you are designing or sourcing components for a blood pressure monitor, the phrase is useful. Human error and product misuse should be part of your component decision. More on that below.
Scenario A: High-volume consumer product with a tight BOM
When you are buying 10,000 or 100,000 pieces for a consumer product, a fraction of a cent matters. But the total cost still matters more than the ticket price. According to the KEMET online catalog at kemet.com, the portfolio includes ceramic capacitors, tantalum capacitors, relays, and connectors. I start every part request with the latest datasheet from that catalog, not with a secondhand screenshot or an old BOM.
For standard decoupling on a home blood pressure monitor, I usually start with KEMET MLCCs. Dielectric selection is simple: X7R or X5R for most bypassing, C0G if you need stable capacitance in a timing circuit. Tantalum capacitors often make sense in power supply outputs, but not because ‘tantalum is more reliable.’ Tantalum is a different tool. Use it when you need stable bulk capacitance in a small package and the voltage derating is respected.
Relays and connectors at high volume
Kemet relays are common in small appliances and medical home devices. If a blood pressure monitor has a pump or valve, the relay has to handle the electrical load, not just the coil voltage. I once chose a relay based on steady-state current and missed the inductive inrush of the pump. I caught it during the design review because I finally looked at the application note. That was a lucky catch. I don’t like relying on luck.
Connectors follow the same rule. A connector rated for 20 insertion cycles is fine for a PCB that is assembled once. It is wrong for a monitor where the user may pull the cuff connector out every day. Look for plating and locking clips. Sometimes you can save $0.08 by switching to a generic part, but if that generic part fails the pull test, $0.08 was not your real cost.
Five minutes of verification saves five days of correction.
Scenario B: Mid-volume, reliability-critical product
Hospitals, industrial controls, transportation, and public infrastructure products are different. Production volume is lower, but failure cost is higher. I slow down in this scenario. We require traceable sources, documented part numbers, and a written reason why the part will survive the application.
For Kemet relays, I check three things: coil voltage, contact load, and expected mechanical/electrical life at the real load. The same contact current can shorten relay life if the load is inductive or if the switching frequency is higher than normal. Document that before you order.
Connectors in reliability-critical products should be selected for mating cycles and environmental stress. If a board-to-board connector sits in a control cabinet that is removed for service twice a year, a 50-cycle connector might be enough. If it is in an infusion pump, the internal flexing and cleaning chemicals change the requirement.
On a recent legacy BOM, the engineer wrote only ‘8110’ for a connector. It sounded like a relay socket to me. The generic replacement looked right, but the latch was plastic instead of metal. We checked the original manufacturer drawing and found that the original part had a different retention force. The 30-minute verification cost nothing compared to the 300-unit rework it prevented.
Tantalum capacitors also get extra attention here. KEMET datasheets contain voltage derating instructions. I am not an electrical engineer, but I know enough to ask whether the voltage derating is captured in the schematic notes. If it is missing, I ask for a review before approval. It is much cheaper to review a design than to recall a production batch.
Scenario C: Prototype, repair, or short-run products
If you need one relay for a test fixture or 50 connectors for a repair run, ignore half the advice above. Unit price is not your main concern. Availability is.
For a prototype, buy from an authorized distributor that has stock, even if the unit price is higher. The cost of waiting a week is bigger than the cost of a component. Do not force a long lead-time part into a short lead-time project.
Still check the part revision. KEMET changes datasheets and part numbers over time. ‘Same as last time’ is not a configuration management process. In 2023, I assumed an MLCC package was identical to the previous revision; the new part had a different capacitance tolerance. We caught it because a technician noticed the label. Verify anyway.
How do you know which scenario fits you?
Use these questions:
- What is your annual quantity? Above 50,000 pieces usually points to Scenario A. Under 500 pieces usually points to Scenario C.
- What happens if the part fails? A consumer return is Scenario A. A stopped production line or a safety-related failure is Scenario B.
- Does your customer require traceability? If yes, buy through an authorized KEMET distribution channel and ask for lot traceability documentation.
- Is the design still moving? If the schematic is changing every month, don’t commit to a custom annual contract.
- Which past mistake worries you most? Use that as a requirement. If you were burned by an untested connector, add a pull test.
The phrase ‘prevention over cure’ sounds like a slogan, but it has a specific financial meaning in procurement. Every check at the beginning reduces the probability of a bigger cost at the end. I built a checklist after my third mistake. It is boring. It still saves me from the expensive moments.
Final thought
If you actually needed ‘Kemet lapping’ for lapping and polishing, this article is not your answer. If you are sourcing KEMET relays, connectors, MLCCs, and capacitors, don’t let the lowest headline price make the decision. Check the datasheet, check the reliability data, check the real failure mode, and calculate total cost. Then choose the scenario that matches your product.
That extra check is not bureaucracy. It is cheap.
