# Network Transformer Sample Evaluation: Measurement Protocol, Comparison Framework, and Sample-to-Production Checklist > Source: > Published: 2026-07-14 08:56:31+00:00 Structured approach to requesting, measuring, and qualifying network transformer samples before production commitment. Sample Request Specification Template pythonSAMPLE_REQUEST = { # Required fields — specify ALL before contacting supplier "speed_grade": "1000BASE-T", # or "10/100BASE-TX" "package": "SMD-16", # SMD-8 / SMD-16 / THT "poe_rating": "802.3at", # None / 802.3af / 802.3at / 802.3bt "temp_grade": "industrial", # commercial (0/+70) or industrial (-40/+85) "isolation_vac": 1500, # V AC minimum; 4000 for medical 2MOPP "quantity_pcs": 10, # 5-20 for evaluation "footprint_ref": "H1102NL-compatible", # or None if no compatibility requirement ``` # Documents to request with samples "required_docs": [ "Datasheet (latest revision)", "OCL vs DC bias characterization (if PoE-rated)", "Reflow profile (peak temp, ramp rate)", "Reel/tape spec (carrier pocket dimensions)", "RoHS/REACH compliance declaration", "Application schematic / reference design", ] ``` } Pre-Solder Measurement Protocol pythonimport time def pre_solder_evaluation(sample_id: str, speed_grade: str) -> dict: """ Run before soldering samples onto test PCB. Returns pass/fail dict with measured values. """ MIN_OCL = { "10/100BASE-TX": 350e-6, # 350 µH "1000BASE-T": 1000e-6, # 1000 µH } ``` results = {} # 1. Dimensional check print(f"[{sample_id}] Step 1: Measure footprint vs. datasheet land pattern") print(" → Check: pin pitch, pad dimensions, body keepout") print(" → Mismatch here = redesign before production — catch it NOW") results["footprint_ok"] = input(" Footprint matches? (y/n): ") == "y" # 2. OCL measurement print(f"\n[{sample_id}] Step 2: OCL — LCR meter @ 100kHz / 0.1V RMS / 0A bias") ocl_measured = float(input(" Measured OCL (µH): ")) * 1e-6 ocl_min = MIN_OCL[speed_grade] results["ocl_measured_uH"] = ocl_measured * 1e6 results["ocl_pass"] = ocl_measured >= ocl_min results["ocl_margin_pct"] = round((ocl_measured / ocl_min - 1) * 100, 1) # 3. DCR measurement print(f"\n[{sample_id}] Step 3: DCR — 4-wire method, both windings") dcr_pri = float(input(" DCR primary (Ω): ")) dcr_sec = float(input(" DCR secondary (Ω): ")) results["dcr_primary_ohm"] = dcr_pri results["dcr_secondary_ohm"] = dcr_sec results["dcr_total_ohm"] = round(dcr_pri + dcr_sec, 3) # 4. Hipot test print(f"\n[{sample_id}] Step 4: Hipot — 1500V AC, 60 seconds") results["hipot_pass"] = input(" Pass (zero breakdowns)? (y/n): ") == "y" # Summary results["overall_pass"] = all([ results["footprint_ok"], results["ocl_pass"], results["hipot_pass"], ]) return results ``` Functional Test Protocol After pre-solder checks PASS → solder onto test PCB, then: Test 1: Link establishment Scope: Connect to GbE switch at rated speed (100M or 1G) Pass: Link up within 5 sec, no auto-negotiate fallback Test 2: Traffic throughput (1 hour sustained) Tool: iperf3 / RFC 2544 test Pass: Zero packet errors, no link drops Test 3: Cable length sensitivity Test: 1m / 50m / 100m cable lengths Pass: Stable link at all three lengths Test 4: PoE power delivery (if applicable) Test: Apply max rated current (350mA / 600mA / 960mA) for 30 min Measure: Transformer temperature rise (IR camera or thermocouple) Pass: Tj ≤ (rated Tmax − 15°C) Test 5: Temperature (industrial grade parts) Test: Repeat Test 1+2 at +70°C ambient Pass: Link up and stable at temperature Multi-Source Comparison Matrix python# Record results from parallel supplier evaluation sources = { "Supplier_A": { "part_no": "VT-GE100AT-SMD", "ocl_measured_uH": 1150, "ocl_margin_pct": 15.0, "dcr_pri": 0.72, "dcr_sec": 0.68, "hipot": "PASS", "link_1m": "PASS", "link_50m": "PASS", "link_100m": "PASS", "price_usd_per_pc": 0.85, "lead_time_days": 7, "moq": 50, }, "Supplier_B": { "part_no": "HX-GBE-16P", "ocl_measured_uH": 1010, # barely above 1000µH minimum "ocl_margin_pct": 1.0, # low margin — temperature risk "dcr_pri": 0.91, "dcr_sec": 0.88, "hipot": "PASS", "link_1m": "PASS", "link_50m": "PASS", "link_100m": "FAIL", # ← issue "price_usd_per_pc": 0.65, "lead_time_days": 14, "moq": 500, }, } Sample-to-Production Checklist Week 1: [ ] Send complete sample request with spec sheet [ ] Receive samples + documentation package via DHL Week 2: [ ] Dimensional check (footprint match) [ ] OCL / DCR / Hipot measurements on all samples Week 3: [ ] Solder onto test PCB, functional tests 1-3 Week 4: [ ] PoE thermal test (if applicable), temperature test Week 5: [ ] Compare multiple sources, select primary + alternate Week 6: [ ] BOM update with approved part numbers Week 7: [ ] Supplier qualification docs (ISO cert, CoC, test report) Week 8+: [ ] First production order (confirm lead time for required quantity) Voohu Technology — [www.voohuele.com](http://www.voohuele.com) Samples from stock | MOQ 50pcs | DHL 3–5 days | Japan / Korea / SE Asia | OCL bias data included