Murata Rush Order Checklist: Space Qualified SAW Filters, LQW Inductors, and C300 Capacitors

Two weeks ago, I was on the phone at 6:30 in the morning because a customer’s board had a Murata LQW inductor that no one could find. The schematic called out C300, and the design engineer was sure it was just a capacitor. It wasn’t. We sorted it out, but only because we had a checklist.

I’m the person who coordinates emergency parts orders. Not the engineer, not the buyer—the person in between who has to get the right part to the right place before the deadline becomes a crisis. I’ve handled 200+ rush jobs in the last decade, and 47 in the last quarter alone, with 95% on-time delivery. This article is the checklist I use when a Murata part has to be on site yesterday.

This is for anyone who needs Murata parts fast—prototype builds, repair line restocks, or a board spin that’s already late. It covers six steps. Step 1 is the boring one, and it’s the one that saves the most time.

Step 1: Pull the exact part number, not the description

It’s tempting to think “Murata space qualified SAW filter” is enough to search with. It isn’t. Murata makes dozens of SAW filters, and a space-qualified SAW filter can have a part number that only matters for one frequency, package size, or electrical spec. The same goes for a Murata LQW inductor. The series name tells you the family; the suffix tells you inductance, tolerance, and packaging.

Here’s the part that trips up a lot of people: C300 is not a Murata part number. In your BOM, C300 is the reference designator on the schematic. The actual component is a 0.1 µF MLCC, or a 100 pF COG, or whatever value is printed in the schematic next to C300. If you call a distributor asking for “C300,” you’ll get a blank stare. Get the value, the footprint, and the voltage rating before you call.

Find the full part number in three places: the schematic, the BOM’s manufacturer part number field, and the original Murata datasheet. Each one should agree. If they don’t, stop and fix that before you order. (Note to self: always check the drawing revision before committing to a part. I learned that the hard way.)

Step 2: Check official Murata sources first

When I’m triaging a rush order, the first thing I do after confirming the part number is go to Murata’s official website (murata.com) and open the product page. According to Murata’s published documentation, the LQW series is designed for high-frequency RF circuits, and the SAW filter selection page lists the actual insertion loss and package dimensions. That sounds obvious, but you would be surprised how many people start with a distributor search and end up with the wrong series.

Murata Manufacturing Co., Ltd. also owns several subsidiaries, including Murata Power Solutions, Inc., and their product pages may use different order codes. Compare them against the main Murata datasheet before you tell your purchasing person anything.

Authorized distributors are your first stop, not because I have a marketing deal, but because their stock is traceable and less likely to be counterfeit. In a rush, it’s tempting to take the first Google result that says “in stock.” I’ve lost too many hours to sellers who listed “N/A” in the date code field and promised documentation after the fact. (Ugh.)

Small doesn’t mean unimportant. If you’re ordering 5 pieces, a good distributor treats that the same way they treat 5,000. The ones that roll their eyes are the ones I stop calling.

Step 3: Ask hard questions about traceability and qualification

For a Murata space qualified SAW filter, traceability is not optional. If the part is specified for a space program, the datasheet should state the qualification standard—often ESCC or a MIL-SPEC program. Ask for the lot traceability report and the actual date code. If the distributor cannot provide them, then for your purposes, it’s not a space-qualified part. It’s just a SAW filter that has been on someone’s website for six months.

The surprise wasn’t the price of an expedited traceable part last month. It was how many third-party listings said “I have it” and then went silent when I asked for a lot number. That silence is a clue, not a coincidence.

For commercial parts, traceability matters less, but date code and storage still matter. Moisture-sensitive devices need to come in the original sealed moisture barrier bag if they’ve been sitting on a shelf. I know this is boring. It gets more interesting when you’re holding a board that won’t boot because the solderability of an old inductor died.

Step 4: How to use a multimeter to verify parts before assembly

A multimeter won’t tell you if a SAW filter performs at 2.5 GHz. It will tell you if the part is dead or shorted before you go through the trouble of assembly. Here’s the process I use.

1. Put the multimeter in continuity mode. Touch the probes together first. If no beep, the problem is the meter, not the part.
2. For a Murata LQW inductor, measure between the two terminals. You’re looking for a low DC resistance—close to 0 Ω. If it reads open, it’s a cracked coil or a broken termination.
3. For a capacitor like the one at C300, use the capacitance mode if your meter has it. A reading that is way off from the printed value is a red flag. If the meter shows a short, reject the part. In-circuit readings can be misleading, so remove one leg when in doubt.
4. For a SAW filter, measure between each pin and ground. A dead short to ground is a rejection reason.

The multimeter is not the final word. It’s the first word, and it’s cheap insurance.

Step 5: Estimate real lead time, then add a buffer

It’s tempting to think “if the courier says overnight, I’m fine.” Overnight starts after the distributor picks the part, and picking does not happen at midnight. In March 2024, I had a customer who needed a Murata LQW part 36 hours before a board spin. The part was in stock, but the time zones, credit check, and shipping cutoff meant it left the warehouse later than expected. We still made it, but the buffer was gone.

Now I add 20% to every quoted lead time. If a distributor says 3 days, I plan for 4. If they say 1 day, I plan for 36 hours. Does that feel pessimistic? Yes. It has also kept my on-time delivery above 95% for four quarters in a row.

For a truly critical order, paying for expedited freight is not waste. That $80 overnight fee is annoying. The cost of a missed qualification window is a thousand times worse.

Step 6: Know when to say no

Not every rush order can be saved. If the only “stock” is a pile of parts from a random reseller with no traceability, walk away. I do not want to be the person who delivers a counterfeit part to a customer and then has to explain why their board failed.

And for a space qualified part, do not substitute without engineering approval. A similar Murata LQW with a slightly different Q might work in an RF filter, but only if the system engineer signs off on it. Most buyers focus on how quickly they can get a part. They completely miss whether the tested land pattern on the replacement matches the original datasheet. That is the question that should make you stop.

When you do find the right part, and it’s real, and it’s on the bench? There’s something satisfying about a BOM going from red to green after three days of chaos. That’s the part of the job I still like.

Common mistakes I see in rush Murata orders

• Ordering by “C300” instead of the actual capacitor value.
• Assuming the space qualified SAW filter part number from one program is the same as another. It almost never is.
• Skipping the datasheet and trusting a distributor’s cross-reference system.
• Using a multimeter only to check if a part physically looks the same, and missing a dead short to ground.
• Waiting until Friday afternoon to start an order that needs Monday delivery. (I have done this too.)

The last one is a confession, not advice. The checklist above works in a real emergency, but it works even better on Tuesday.