A probe design team at a medical imaging startup told us they'd been waiting 11 weeks for cable prototypes from their first supplier. Eleven weeks—for five sample cables. By the time the cables arrived, the probe design had iterated twice and the cable spec was already obsolete. They needed new samples, which meant another long wait. The prototype-iterate-prototype cycle was consuming more calendar time than the actual probe engineering. When they switched to us, the first batch of samples shipped in 18 days from spec approval. The second iteration—after they tested and tweaked the specification—shipped in 12 days because we already had the base cable in stock.
Medical cable assembly prototype speed is determined by three things: how complete the specification is when it arrives, whether the raw cable and connectors are in stock, and how efficiently the manufacturer can execute on small quantities. At FRS Technology, we've built our prototyping process specifically for the iterate-fast cycle that medical device development requires. Here's how the process works and where the time typically goes.
Week 1: DFM Review and Material Confirmation
The first step isn't building anything—it's making sure the specification is complete, manufacturable, and unambiguous. Our engineering team reviews the cable specification against our manufacturing capabilities and flags any issues: dimensional tolerances that our equipment can't hold, material combinations that are incompatible (like TPU jacket with autoclave sterilization), connector pin pitches that are too tight for manual termination at the specified AWG, or test requirements that need clarification.
The DFM (Design for Manufacturability) review typically takes 2-3 business days. We return a marked-up specification with comments on any items that need clarification or modification, along with recommendations for alternative approaches where applicable. Honestly, this review catches specification issues on about 40% of new cable programs—problems that would otherwise surface during assembly as prototype failures, wasting time and material.
Simultaneously, we confirm material availability. For standard constructions—42-44 AWG, solid PTFE dielectric, braided shield, FEP jacket, with I-PEX 20453 or Hirose DF81 connectors —we maintain buffer stock of raw cable and connector inventory. These programs can proceed immediately after DFM approval. For non-standard constructions (unusual AWG, ePTFE dielectric, custom connectors), material procurement adds 1-3 weeks to the timeline, which is the primary driver of the difference between a 3-week and a 5-week prototype delivery.
Week 2-3: Cable Production and Assembly
Once the spec is approved and materials are confirmed, production begins. For a typical 128-channel ultrasound probe cable prototype:
Day 1-2: Cable preparation. Raw cable is cut to length with margin (we add 10% to the specified length to allow for trim during termination). For bundled cables, individual elements are sorted by measured impedance or VoP if phase matching is specified, then stranded on the planetary cabling machine. A 128-channel bundle takes about 4-6 hours to strand, including setup and quality checks.
Day 3-5: Termination. This is the time-intensive step. Each end of the cable requires individual stripping and soldering of every channel. A 128-channel cable with I-PEX connectors takes 70-90 minutes per end for an experienced operator. For a batch of 5 prototypes, termination alone consumes about 12-15 hours of operator time. Prototype batches run on our standard production equipment but with dedicated operators who have the flexibility to adjust process parameters if the first unit reveals any termination challenges.
Day 5-7: Overmold and strain relief. Strain relief application, any overmolding, jacket trimming, and cosmetic finishing. For prototypes, we use the same strain relief materials and processes as production to ensure the prototype is mechanically representative. Shortcuts on strain relief at the prototype stage lead to misleading flex life data during evaluation.
Week 3-4: Testing and First Article Inspection
Every prototype cable assembly gets 100% electrical testing—every channel, every parameter. The test suite for a medical Micro Coaxial Cable prototype typically includes:
| Test | Method | Typical Acceptance Criteria | Time per Assembly |
|---|---|---|---|
| TDR impedance profile | Time Domain Reflectometer, all channels | 50Ω ±spec per channel, full-length profile | 15-25 min (128 ch) |
| Continuity | Low-resistance ohmmeter, all channels | <2Ω end-to-end | 10-15 min |
| Insulation resistance | Megohmmeter @ 500 VDC | >100 MΩ conductor-to-shield | 10-15 min |
| Hipot (dielectric strength) | 1,500 VDC, 1 second, all channels | No breakdown, leakage <5 µA | 15-20 min |
| Capacitance | LCR meter @ 1 kHz, sample channels | Within spec pF/m ±tolerance | 5-10 min |
| Phase matching (if specified) | TDR propagation delay, all channels | ±spec % across all channels | 15-25 min |
| Visual inspection | 10-20× magnification, all terminations | Per IPC/WHMA-A-620 Class 3 | 15-20 min |
The first article inspection (FAI) report documents all measurements for the first cable assembly in the prototype batch, with each measurement compared against the specification. Any out-of-spec measurements are flagged with root cause analysis and corrective action. The FAI report ships with the prototype batch and serves as the baseline for any future production.
For prototype batches at FRS Technology, we include the full FAI report and individual test data for all units in the batch at no additional charge. Some manufacturers charge separately for FAI documentation—verify this upfront to avoid surprise costs.
What Slows Prototyping Down—And How to Avoid It
In our experience, the three biggest causes of prototype delays are all avoidable:
Incomplete specifications account for about 50% of delays. Missing connector part numbers, undefined test criteria, ambiguous channel-to-pin mapping, or unstated sterilization requirements all require clarification cycles. Each clarification email adds 3-5 business days. Using a complete RFQ template before engaging the cable manufacturer eliminates most of these delays.
Non-stock materials account for about 30% of delays. Custom connectors with 4-6 week lead times from the connector manufacturer are the most common culprit. If your design uses a proprietary connector, order the connectors directly and ship them to the cable manufacturer—don't wait for the cable manufacturer to procure them through their own supply chain, which adds handling time and markup.
Specification changes mid-prototype account for about 20% of delays. Changing the cable length, adding channels, or switching connector types after production has started usually means restarting from scratch. If you anticipate specification evolution, consider ordering the first batch as "engineering samples" with the understanding that a second, specification-final batch will follow. This sets expectations correctly and avoids the frustration of redesigning a prototype that was built to a preliminary spec.
Prototype Iteration: The Second Round Is Always Faster
First prototypes take 3-5 weeks. Second-iteration prototypes—where the cable specification is modified based on testing of the first batch—typically take 2-3 weeks. The acceleration comes from several factors: the raw cable is already in stock (we produced excess on the first run), the termination fixtures are already built, the operators are familiar with the assembly, and the DFM issues have been resolved.
We've structured our prototyping process to support rapid iteration. After the first prototype batch ships, we retain all production setup data—fixture configurations, laser parameters, test programs—so that the second iteration starts from a known baseline rather than from scratch. If the specification change is minor (cable length change, connector pin swap, different strain relief material), we can often turn around a revised batch in 7-10 business days.
This iteration speed matters because medical device development is inherently iterative. The probe design team tests the first cable, discovers that the flex life needs improvement at the strain relief, adjusts the strain relief design, and needs a revised cable. If each iteration takes 8-12 weeks (common with larger suppliers), the cable becomes the development schedule bottleneck. If each iteration takes 2-3 weeks, the cable keeps pace with the design team's tempo.
From Prototype to Production: What Changes
A well-executed prototype should be production-representative—built with the same materials, processes, and quality standards as the eventual production cable. But some things legitimately change when transitioning from 5 prototypes to 500 production units:
Fixturing gets dedicated. Prototype termination uses general-purpose fixtures; production runs justify custom termination fixtures that reduce operator variation and improve throughput. Testing gets automated. Prototype testing is largely manual; production testing uses programmed test sequences that run faster and generate consistent documentation. Yield expectations tighten. We accept higher rework rates on prototypes (10-15%) than on production (target <5% rework). And pricing adjusts—prototype pricing includes NRE for first-article setup, DFM review, and engineering time that amortizes to near-zero on production volumes.
If you're ready to start a medical cable assembly prototype program—or if you're frustrated with your current supplier's prototype timeline— send us your cable specification . We'll confirm material availability, provide a firm prototype delivery date, and quote both the prototype batch and anticipated production pricing so you can plan your program with confidence.
One question that's worth asking yourself before ordering prototypes: are you prototyping the cable, or are you prototyping the device? If the device design is still changing weekly, ordering precision cable prototypes may be premature—a hand-built mock-up cable might serve your functional testing needs at a fraction of the cost and lead time. Save the full-spec prototype for when the cable specification is at least 80% stable. We'd rather tell you to wait two weeks and get it right than rush a prototype that'll be obsolete before it arrives.
Related Products
From prototype quantities through volume production, FRS Technology manufactures the assemblies described above. Related products:
Send your drawing or spec sheet and get a quote within 48 hours. Prototype quantities start at 5 assemblies.
