1. Material properties and selection
\nHigh TG base material requirements
\nTg value: \u2265170\u00b0C (130~140\u00b0C for conventional FR-4), typical materials include:
\nIsola FR408HR (Tg=180\u2103, Dk=3.8, Df=0.010@1GHz)
\nShengyi S1000-2M (Tg=175\u00b0C, cost 30% lower than imports)
\nThermal Stability:
\nT288 heat-resistant time: \u226560 minutes (5~15 minutes for conventional FR-4), preventing delamination by multiple reflow soldering.
\nZ-axis CTE: \u226450 ppm\/\u00b0C (60~80 ppm\/\u00b0C for conventional FR-4), reducing the risk of thermal cycling hole wall fracture.
\nThick Copper Foil Specifications
\nCopper thickness range: 2~10 oz (70~350 \u03bcm), selected according to current demand:
\n2~3 oz: for DC-DC converters, motor controllers (carrying 20~50A current).
\n4~6 oz: High power inverter, power bus (carrying more than 100A current).
\n10 oz: Extreme scenarios (e.g. welding machine, energy storage system), special etching process required.
\n2. Design Specifications and Core Challenges
\nKey points of line design
\nLine width\/spacing compensation:
\nThick copper etching side corrosion is serious, need to increase the line width compensation (e.g. 3 oz copper foil needs to be extra 20%~30% wider).
\nMinimum pitch: \u22658mil (200\u03bcm, 3 oz copper foil) to prevent short circuit.
\nCurrent carrying capacity optimization:
\nCurrent Carrying Capacity Calculation: Based on IPC-2152 standard, 3 oz copper foil, 10\u2103 temperature rise, 100mil line width can carry about 30A DC.
\nCopper Foil Topology: Laying copper in a grid pattern or localized thickening (copper block embedding) is used to reduce resistance and heat buildup.
\n3. Reliability Test Criteria
\nThermo-mechanical reliability:
\nTg test: DSC method (Differential Scanning Calorimetry) to verify the actual Tg \u2265 nominal value.
\nThermal cycle test: -40\u2103~150\u2103, hole resistance change <5% after 1000 cycles (IPC-6012 standard).
\nCurrent load test:
\nContinuous current load: 1000 hours of continuous operation at rated current, temperature rise <40\u2103.
\nInstantaneous overload: 2 times rated current impact (1 second\/time, 100 times), no burnout or delamination.<\/p>\n
4. Typical application scenarios
\nNew energy vehicle OBC (on-board charger)
\nIndustrial inverter<\/p>","protected":false},"excerpt":{"rendered":"
1.New energy vehicle OBC (on-board charger)
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