Network Transformer Sample Evaluation: Measurement Protocol, Comparison Framework, and Sample-to-Production Checklist

A developer published a structured protocol for evaluating network transformer samples before production commitment. The guide includes a sample request template, pre-solder measurement steps, functional tests, and a multi-source comparison matrix. The approach aims to catch footprint mismatches, OCL margin issues, and temperature risks early in the evaluation process.

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