We receive about 40 RFQs per month for custom Micro Coaxial Cable assemblies. Roughly a third of them are missing critical information that prevents us from quoting accurately—or at all. The result: a round of back-and-forth emails asking for the details that should have been in the original request, pushing your quote timeline from 3 days to 3 weeks. On the other end, about 10% of RFQs come with so much unnecessary detail (full regulatory submission documents, 80-page quality manuals) that the actual cable requirements are buried.
An effective cable assembly RFQ hits the sweet spot: enough technical detail for the manufacturer to quote accurately, enough commercial context for them to quote competitively, and nothing else. Here's what that looks like in practice.
Step 1: Define What You're Actually Buying
This sounds obvious, but "I need a micro coaxial cable" doesn't give a manufacturer enough to work with. The minimum information for any cable assembly RFQ:
Cable specification. At minimum: gauge (AWG), impedance (50Ω or 75Ω), number of channels, and cable length with tolerance. Ideally also: dielectric material preference (FEP, ePTFE, PFA), conductor type (SPC or bare copper), and whether the cable needs to be supplied as a multi-channel bundle or individual elements. If you have a specific cable part number you're currently using (Junkosha MCT-42, Proterial SonoEase, etc.), include it as a reference.
Connector identification. Specify connectors at both ends by manufacturer and part number: "End A: I-PEX 20453-030T, End B: Hirose DF81-30P-LCH." If the connector isn't determined yet, describe the mating connector on your PCB or device so the manufacturer can recommend options. Saying "we need a connector" without specifying which end connects to what is the fastest way to get a quote that doesn't match your actual need.
Cable length and routing. Total length from connector to connector, and any constraints on cable routing—minimum bend radius, maximum bundle OD, whether the cable passes through a specific opening or strain relief. A sketch or photo of the cable routing path is worth a thousand words of written description. Honestly, the best RFQs we receive include a simple hand-drawn sketch on a napkin photo—it tells us more than paragraphs of text.
Step 2: Communicate the Application Context
Telling the cable manufacturer what the cable does—not just what it is—dramatically improves the quality of the quote and any DFM (design for manufacturability) feedback you'll receive.
"This is for an endoscope imaging cable that routes through a 5 mm instrument channel and must survive 500 EtO sterilization cycles" tells us to specify FEP jacket, silver-plated conductor, appropriate flex life testing, and ISO 10993 biocompatible materials. Without that context, we might quote a PVC-jacketed cable that meets the electrical spec perfectly but fails the first sterilization cycle.
Application context also helps us draw on relevant experience. If you tell us you're building a 128-channel ultrasound probe cable , we immediately know you'll need phase matching , specific connector interfaces, and probably a particular cable gauge based on your bundle diameter constraint. We can quote proactively for requirements you might not have listed yet—saving you the "oh, we also need..." follow-up cycle.
Step 3: State Your Volume and Timeline Clearly
This is where many RFQs are intentionally vague, and it costs the requester money. Cable assembly pricing is highly volume-dependent—a 128-channel assembly might cost $350 at 50 units and $180 at 5,000 units. If your RFQ says "quantities TBD," the manufacturer either quotes conservatively (high) to protect margin or quotes aggressively (low) to win the business and then renegotiates later. Neither outcome serves you well.
Be specific: "We need 20 prototypes by Q3 2026, expect 500 units first production run Q1 2027, with annual volume ramping to 3,000 units by 2028." This lets the manufacturer quote each phase appropriately—prototype pricing is always higher, and they won't penalize your production price for low prototype volumes if they can see the ramp.
Timeline matters equally. "ASAP" isn't a delivery date. "Prototype delivery by August 15, 2026" is. If your timeline is aggressive, say so—some manufacturers can expedite for a premium, but only if they know the urgency upfront. We've had RFQs where the customer didn't mention their timeline until after quoting, then told us they needed prototypes in 10 days. We could have accommodated that with 3 days' advance notice. With zero notice, it wasn't possible.
The 6 Most Common RFQ Mistakes (and How We See Them)
| Mistake | What the Manufacturer Sees | How to Fix It |
|---|---|---|
| No connector specified | Can't quote assembly labor, connector cost, or tooling—responds with clarification request, adding 5–7 days | Specify connector part numbers or at minimum the mating connector on your PCB |
| Cable length not specified or "approximately 2 meters" | ±10% length tolerance vs. ±5 mm tolerance changes cable cost, connector strain relief design, and phase matching approach | Specify exact length ±tolerance: "2,000 mm ±10 mm" |
| Volume stated as "10K+" without phasing | Unknown ramp profile—manufacturer can't plan capacity or material procurement; quotes conservatively | Break volume into phases: prototype, first run, annual steady-state |
| Over-specifying (sending full device DHF to the cable vendor) | Cable requirements buried in 100+ pages of system documentation; engineer spends hours extracting relevant specs | Extract cable-relevant specs into a 1–2 page cable specification document |
| Specifying cable by brand/part number only ("we need Junkosha MCT-42") | Manufacturer can supply equivalent but can't quote Junkosha product directly; unclear if you'll accept alternatives | Spec by performance ("50Ω, 42 AWG, ePTFE, SPC") with brand reference: "equivalent to MCT-42" |
| Not mentioning sterilization or biocompatibility requirements | Manufacturer quotes standard materials; rework required when medical requirements surface later | State upfront: "Cable requires autoclave compatibility and ISO 10993 biocompatibility" |
Step 4: Include Your Testing and Quality Requirements
For medical cable assemblies, testing requirements can represent 15–30% of the total assembly cost. If your RFQ doesn't specify testing, you'll get a quote based on the manufacturer's standard protocol—which might be more or less than what your quality system requires.
Specify what you need tested on every assembly: impedance (TDR or VNA), continuity, insulation resistance, hipot/dielectric withstand voltage, pull force at connectors, and any application-specific tests (phase matching, insertion loss at operating frequency). If you require 100% testing (every unit) versus sampling-based testing (AQL), say so—100% testing adds significant cost but is standard for medical devices.
Also specify what documentation you need with each shipment: certificate of conformance (CoC), test data reports, material certifications (RoHS declaration, biocompatibility certificates), and lot traceability records. Manufacturers who routinely serve medical OEMs will have these processes in place, but the scope and format vary. Aligning on documentation requirements during quoting avoids friction during production.
Step 5: Ask the Right Questions
An RFQ isn't just about getting a price—it's about evaluating whether the manufacturer can actually execute. Include these questions in your RFQ to separate capable suppliers from optimistic ones:
"What is your current lead time for prototype and production quantities of this assembly?" A specific answer ("3 weeks for prototype, 5 weeks for production") is better than "competitive." If they can't commit to a timeline before receiving your order, they probably can't commit after either.
"Do you have experience manufacturing cable assemblies for [your application type]?" Past experience with ultrasound probes, endoscopes, NDT instruments, or whatever your application is means the manufacturer has already solved the process challenges specific to your device category. They'll catch problems earlier and quote more accurately.
"What is your typical first-pass yield on assemblies of this type?" This question separates manufacturers who track quality metrics from those who don't. A supplier who can tell you "96.5% on 42 AWG with I-PEX termination" has process control. One who says "very high" doesn't have the data.
"Can you provide a DFM review before quoting?" A manufacturer willing to invest engineering time reviewing your design before committing to a price is one that takes accuracy seriously. DFM feedback like "your specified connector doesn't mate reliably with this cable OD—consider switching to the -020T variant" saves you a failed prototype build.
Step 6: Evaluate Responses Beyond Price
When quotes come back, the temptation is to sort by unit price and call the cheapest supplier. For commodity cables, that might work. For custom medical micro coaxial assemblies, the lowest price often correlates with one or more of: under-scoped testing, optimistic yield assumptions, or inexperience with the complexity you've specified.
Evaluate on five dimensions: price (of course), but also lead time reliability (ask for references), technical capability (did they provide useful DFM feedback or just regurgitate your specs?), quality system maturity (ISO 13485 certified, or just "in process"?), and communication responsiveness (how long did it take them to respond, and did they answer all your questions?).
In the 400+ prototype and production programs we've supported, the projects that go smoothly share one characteristic: the OEM invested time in writing a clear RFQ and evaluating responses thoroughly before placing the order. The projects that struggle usually started with a vague request, a quick price comparison, and then months of rework fixing misaligned expectations.
If you're preparing a cable assembly RFQ and want to make sure you've covered the essential specifications, send us your draft specification or RFQ for a complimentary DFM review —we'll provide feedback on completeness and flag any missing information before you send it out for competitive bidding. No obligation, and it'll save you at least one round of clarification emails regardless of who you end up working with.
The Thing Most Engineers Skip
Here's the detail that separates a good RFQ from a great one: include your failure criteria. Tell the manufacturer not just what you need the cable to do, but what constitutes a failure. "Impedance must be 50Ω ±3Ω at 23°C" is a specification. "Any channel exceeding ±3Ω at any point along the cable length at temperatures between 15°C and 40°C is a reject" is a failure criterion. The distinction matters because it determines how the manufacturer tests, how they set process limits, and how they handle borderline results. Without clear failure criteria, every borderline unit becomes a negotiation—and that's a waste of everyone's time.
Related Products
Our production covers 4 to 512 cores in 36-50 AWG, with ePTFE dielectric and 100% electrical inspection on every channel. Related products:
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